@@davidt8087 What is the point of your life ? We already have billions of people and you can't provide anything the other billions won't. Replicate whatever answer you choose for yourself to the question you asked.
I remember a few years ago, where a group of taxi drivers mounted illegally small tyres on their cars, so that the system would overcharge the customer, since it relied on the car's speed to calculate distance driven.
actually, as a delivery man, i'm quite familiar with this system here in Hungary. our fiats overread by around 6km/h, and fixed cameras have a given tolerance (by law) depending on speed, in 50km/h areas its 62km/h. so in theory you could pass the camera in a 50 zone at 67, and not get a ticket. I usually play it safe as you say in the video, and never exceed 60. and it's working, I haven't gotten any tickets so far. at least not from fixed cameras.
I stick to the 10% rule.. if Im supposed to go 50 Im going 55 on the speedometer and so on. But when I go through a route that I know very well (where the straights are, where it is possible to safely ovetake, where the holes are in the road, where the cops like to measure the speed etc.), I will push the car. Theres no reason to go 90 on a road that I can perfectly travel at 150 without endangering myself nor anyone else and also without the risk of getting a ticket.
@@MisoElEven If something changes you're going an extra 60kmh faster though. And what if someone doesnt realise you're going that much faster and pulls out in front of you?
@@Noreceipts400 Theres nothing that can change on that particular road and I can see several km ahead..the faster the overtaking manouver is over the safer it is. What if the driver doesnt see you when youre going the legal 90km/h while the other one is doing 80? Nothing changes, you will crash if he moves to that lane or a car flies into my face from the other side. Seriously, unless the car in front explodes theres nothing that can happen on that particular road. Lets not forget theres not much traffic anyway. If anything I would be more afraid of gypsies crossing the road with their tons of copper and other scrap metal etc. XD in the city where I was born (Košice) theyre aparently going to lower the speed limit on the highway from 130 to 90 and install traffic lights just so they can move the trash they have stolen from one side to the other because if we built a wall again then the EU could sanction us for racism/segregation. Thankfully I dont have to ride through that piece of road anymore. Edit: also you always have to let the car in the left lane go, even if its speeding and youre just moving to the left to avoid a colission with lets say a bus.
wheel speed sensors are usually used for abs and esc. 99% of the time most cars use a speed sensor from the gearbox for the speedo. just FYI. Also the faster you go the futher out your speedo will read
All the cars I have owned show speedo is off by the same absolute amount regardless of speed. The computer reads the speed from sensors and subtracts a given amount…50kph is really 46, 100 is really 96. 120 is really 116. Not a percentage amount, but a fixed amount regardless of speed.
You've missed out a very important part here. Your speedo might be lying, but the car's speed sensor is usually very accurate. Hook a reader up to your car's diagnostic port and access the output from the speed sensor and you will find it is usually very close to the GPS readout (also proving that the speedo is being artificially set to over estimate speed). The whole thing with the speedo over estimating your speed in the UK and Europe is because there are significant fines for manufacturers that issue a speedo that reads a lower speed than the car is actually doing. They don't do it to protect you from speed cameras/limits; they do it to protect themselves. As a slight aside, cars over estimating speed by significant values is not really a good thing, especially if you have a driver that doesn't understand their speedo isn't accurate. A lot of people get this idea that because their speedo says they are doing the speed limit, anybody passing them is speeding. This in turn leads to certain drivers taking it upon themselves to attempt to control other drivers speed. Or you end up with drivers angry at the people they perceive to be speeding, or angry drivers being held up by drivers who are going dangerously below the speed limit. Vehicle technology allows for highly accurate speedo readouts. Let's stop this pandering to manufacturers, pretending that over reporting speed is a good, or even acceptable state. If Mazda can confidently set their speedos to report very close to the correct speed, none of the other main manufacturers have any excuse.
Honestly Mazda is doing a lot of things differently to other manufacturers.. while VW and its brands went the way of 1.0 3 cylinder engines with a turbo (for the low and mid end cars, you can still get a 2l min something more expensive), you have to turn all the assists off every time you start the car, many of them are quite understeery and heavy. Mazda went with 2.0-2.5l 4 cylinder atmospheric engines even for its base models, push one button and all the lane keep etc. shit assists are off until you turn them on again yourself. In Mazda you dont need an automatic gearbox to get 4x4..Even the whole infotainment is done completely differently to the whole industry.. all car manufacturers talk about how its impossible to make "good old cars" anymore while its somehow possible for Mazda. Im not saying their cars are perfect, driving a car with no turbo after driving with it for a while will feel a bit slow but the nice throttle adjustment mid corner is something I personally cant let go of. From that I would assume that overestimating the speed is just a safe bet, simpler and possibly cheaper way to do it..just like with small turbo engines and everything else. Maybe thats the one thing every manufacturer should copy. It would certainly made roads safer if I didnt have to pass moms in their SUVs when theyre doing 40km/h all the time.
@@MisoElEven Something that could be interesting to note about the choice of engines for given market are the taxes. In many country (including in Belgium where i live), you have a yearly taxe to pay depending on your engine displacement. So people tend to go for smaller engines with turbo in order to pay less. And Belgium is quite expensive in that area (More than France). Which could explain why i don't see a lot of Mazda on the road in Belgium.
That is very interesting. That means the over read could be a constant and not linear with speed. So you would always be 5 kph above irrelevant of speed (appart for when you are at a stop or very slow i assume). I used to think that if you have +5 at 100kph, you might have +10 at 200. Which would make sense if the overread is from the system inaccuracies instead of an electronic margin.
@@guilemaigre14 the over estimating being a fixed amount, or a percentage likely varies by manufacturer and how they are achieving the result. My past couple of vehicles have been a percentage difference. For example, my current main vehicle (an older Nissan X-Trail (T30 model)) reads 33mph on the speedo when the sensor reads 30mph. The speedo reads 78mph when the speed sensor reads 70mph. Would be quite interesting to have details from a range of makes and models to see the difference in how big the speed variance between the on-board computer and the speedo is; and how many are a percentage of speed difference Vs a set speed difference.
This is exactly right. My old Ford Ka reported insanely accurate speeds through the OBD port (+/- 0.3-0.5 km/h) but chose to move the needle less than it was reading.
In many parts of the US, speed cameras can't give automatic tickets. Making this a none issue, following the flow of traffic is generally the only thing to think about
in louisiana (where i am), often the posted limit is 35, but traffic is moving at 55, so if you do 35 you WILL cause an accident. in the US, it's ALWAYS better to follow traffic rather than the speed limit.
@@staterafukumoto in new york, the highway speeds are 55 but you won't catch a single car in the left/middle lanes going below 70. you can also be driving alongside cops doing that speed
@@staterafukumoto In Miami if youre not doing at least 85 in the left lanes which normally at 85-100mph sometimes 105 you getting yelled at with horns blazing that's including the coop excluding State boys
In Oklahoma, the speed limits are anywhere from 60 to 80 on highways. Usually add 5-10 to that and you're safe. My wife and I were recently in Philadelphia and the 55 mph speed limit is more of a suggestion than the law. Go 70-80 or get rear ended. We learned that real quick when I was doing 60 on I-95. I learned then that even the worst drivers in Oklahoma are pretty tame.
I don't have cruise control, but a steady foot. My old ass VW Vento (Jetta 3) overreads by like 3km/h on winter tires and it's pretty much spot on with my summer setup
When I’m doing the legal speed limit of 120km/h in my Lexus, Waze says I’m doing 114km/h, what I find interesting is that the Lexus CT is limited to 180km/h but on the speedometer I’ve reached 190km/h which with Waze is 180km/h so I almost wonder if Lexus knows by how much their speedos are of, limiting to the actual speed and not the speedometer
As another separate comment, I also want to note the effect of the wheel circumference. Back in the early 2000s both myself and my sister owned an E110 Corolla. Mine had the stock 175/65/14 wheels. Hers was modified by the previous owner to run 185/60/14. That's a difference in sidewall height of 2.75mm, or 5.5mm in circumference. On a long-haul trip from Namibia to South Africa we were driving together, and I asked her why she was driving 5km/h below the speed limit. She said she wasn't...
Yeah, that's why it's OK to be slightly speeding most of the time, cause you're actually not speeding at all. But I agree with the regulations - it is far more convenient to drive just a bit slower, without even noticing, than to get a ticket while thinking that the speed was under the limit.
I kinda knew this already since i noticed that gps speed is usually less than the car speed. My dilema is: what about the car odometer? If your car overreads in 99% of the cases, then that means the car odometer is higher than it should be. Also the mileage is worse than the car reports. So, if the car overreports by 5% then for a 60mpg car means 57, not a huge difference, but its a difference
For the odometer it's not particularly important because it's only a general indication rather than a datum point for specific tasks. If you were buying a second hand car a 90000 mile car that has done 85% of those miles on the motorway could be in better mechanical order than a 25000 mile car of the same age that has been used as a courtesy car and ragged every day of its life, also if you're due a service/belt change at 20K it's not likely to matter within +/-15%. Indicated mpg is again never particularly accurate, it's an estimation designed to highlight optimal engine conditions rather than an actual indicator of consumption.
From what i gathered on other comments, the odometer is usually very accurate. It is only when displaying the speed that they add a margin. Now i lack soucres to confirm, but others seems to says so.
I can't say for all odometers of course, but I can tell you for my last couple of vehicles the odometer is not connected to the speedo output. I have mentioned in a comment below that whilst the speedo is often quite inaccurate, the speed sensor on onboard computer monitoring speed in a vehicle is usually very accurate. If you connect to the diagnostic port on relatively modern vehicles, and check the speed sensor output, you will find it is different to the vehicle's speedo output. Odometer figures are based on using that speed sensor. So, for example, when my vehicle's onboard computer reports the speed sensor as running at 70mph (using the EODB (equivalent of the OBD-II port used in North America) port to read data), my speedo with display 78mph. But if I was to run constantly for an hour at that speed, my odometer would increase by 70 miles.
@@damionlee7658 guess overreporting is so bad that they artificially reduce the value. I usually set my cruise control to the gps speed, sometimes 5-10km above it, but it seems really strange. Also modern cars should be able to auto adjust for wheel, since they have a gps internally and they can compare the gps speed to the wheel speed. Tesla can detect wheel uneven wear, this should be easier to do
My E39 528i is exactly 5 kmh over the real speed. The funny thing is that in the hidden menu on the bord computer there is a real speed option which is spot on but must be turned on every time you start the car if you want to use it.
@@xJustInTime it depends on the version of obc you have (big or small screen in the cluster) but there are a lot of tutorials on TH-cam. Normally on all BMWs it's turned on by holding the button to reset the trip odometer for around 10-20 seconds. You have to unlock it as well after you get in, so better check a TH-cam tutorial as it's a but too much to type in a comment.
Having driven many cars both in the US and Europe, I can confirm, almost all cars consistently overread in Europe, but in USA it's much closer. I've heard carmakers do this to make the car feel "faster", as you seemingly reach a higher number sooner than if the speedo was accurate, whilst still staying within the lawful limit. Can confirm, Mazdas are accurate even in Europe.
I learnt about this when I was still in high school, when I got my first car I already knew that 129km on my Speedo was 125km in reality but I also noticed that the accuracy varies depending on how fast you're going.
My GPS sat nav screen was always showing a few KMH over the indicated speed and it annoyed the hell out of me, so I recalibrated mine on my E46 M3 by opeing up the speedo cluster and readjusting the needle.
I've been using the 10% rule for ages. I regularly drive 10% over the speed limit while going through speed cameras and I've yet to get a ticket (other than when I've not known I'm going past a camera).
in maryland, where i live, the fixed speed cameras allow you to go up to 12 miles an hour over the limit, so 37 in a 25 etc... Of course most people dont know this so they slam on the brakes right at the camera and go 10 under the limit then floor it afterwards cuz idiots ...
In Australia a speedo is allowed to be 10% inaccurate. In the past most cars were fairly accurate, but that changed in 2008. Starting in October 2008 car manufactures had to list on the windscreen of a new car its fuel consumption rating. Manufactures soon worked out that they could improve their fuel ratings by making the cars speedos inaccurate. My 2012 Subaru was so inaccurate ( 8% higher ) that I used to have a old phone sitting on my dash that I used as a GPS speedo. No need for the GPS speedo anymore as my current Mercedes is 100% accurate. As a result my Mercedes fuel consumption reading is 100% accurate, not reduced by a false 8% like in my Subaru.
In Australia, regulations (ADR18) required a car built before July 2006 to have a speedo read the actual speed +/- 10%. The vast majority of manufacturers, of course, tried to make the speedo as accurate as possible. In July 2006 that regulation changed, so that a speedo can NEVER read a lower speed than what the vehicle is actually doing, but MAY read up to 10% + 4km/h over the actual speed. So not really a significant change. Except, the national transport authority in Oz ... err ... actively 'encourages' manufacturers to make maximum use of the allowed tolerance. Put simply, it is a strategy to make the speedos in all cars (made after 2006) read high, thereby slowing traffic. So the same result as reducing ALL speed limits across the country by 10% + 4km/h , without the political backlash of doing so. And before you say "but my car here in Australia is made in Europe, so it will be more accurate", let me add a minor detail that was missed in the video. Basically all modern cars get an extremely accurate speed reading from the relevant sensor, and that is what is supplied to the ECU etc. But the ECU then hands that input to the dash display unit, which displays the speed etc. It is in this unit that the speed is 'modified' to read 10% + 4km/h higher than the actual speed. This allows for the odometer to remain accurate, as the 'correction' is not applied to that element of the display. So all the European manufacturers have to do, is a simple software update to the cars coming to Australia, to make the speedo read high, as is required. So to put this in more practical terms. When you are in the Righthand lane of a multilane motorway, trying to overtake at the actual 110km/h speed limit, and there is a car sitting in front of you, slowing you down ... say doing 96km/h (by your accurate speedo or GPS)? Well, his speedo says he is doing 110. Just as the authorities want.
I got called out :D I am definitely doing the math - Waze speed readout + 5km/h tolerance on measuring equipment so in 50km/h I will be usually doing 58km/h on the speedometer and 55km/h on GPS... but I noticed the car having different margins at different speeds and that a GPS speed read-out is wrong if you are going up or down a hill -- so I have to account for that too
That’s interesting. Adds another level to how fast people drive now. Really tempted to test this out now 😂 Edit: tested the theory and yes, my dads 2018 BMW 5-Series does it too, the car was 2 mph above the what the GPS was telling me.
I used to have an E36 and I currently have an E60. Both would consistently show 2mph faster than the GPS showed I was going. The E60 is a little more odd though. I've coded the cluster to show a digital reading of the current speed. If I set my cruise to 72mph, the GPS speedometer on my phone will show 70mph, but the digital reading in my gauge cluster will show 69mph.
The only upside of living in the US is that we generally don't have average speed cams, no one knows how to drive, but the rules only matter when caught, and if you do go the speed limit on the highway you will be killed because no one else will go the speed posted.
My BMW shows 4 MPH on the speedometer over GPS speed indicators. I always suspected this was intentionally done so that the car warranty would be voided sooner than it should have otherwise been.
When I got my first car - a Honda CR-Z - a few months ago at 18, naturally I was super hesitant with my speed & I've actually been wondering ever since why Google maps reads my speed 3mph less than the car does (I assumed it was an inaccuracy on my phone's part). This video's been an awesome help, cheers!!
5:11 Of course, timing for record speed attempts is generally done with external equipment (though I'm sure it's useful for the driver to have an accurate indication too!).
My Mitsubishi Eclipse GT v6 from 2008 reads 10% under. I actually noticed just because 120kmh didn’t feel remotely as fast as it did in my Santa Fe and when tested found that I was completely correct. Living in Ontario Canada, and the car has 150k clicks on it. It’s really neat to know it’s not just a my car problem
Yeah, been aware of this for more than ten years. In my Jetta, I've noticed 33 is 30mph; 44 is 40mph, 54 is 50mph and 66 is 60mph. Have driven past speed cameras hundreds of times at these speeds and not gotten a single ticket.
My mate and i actually figured this one out pretty recently, got a 2010 VE Holden Commodore SV6 and when the dash is spot on 110km/h, phone GPS only shows 105km/h. On a 7 hour drive in Western Australia that 5km/h does add up!!
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When I got my BMW I noticed the speedometer was always reading faster than I was actually going so I researched it and apparently German cars must always over read and never under read the speed. There’s a setting in BMWs that lets you make the speedometer display the actual speed but that’s turned off in the United States. I used an online calculator to figure out what tire size I needed to install to get the true speed reading on my speedometer and installed that size of tires now. They were very close to the original size but made just a small difference in my speedometer and now it’s spot on.
I can tell that at least an NB MX-5 does use the sensors from a gearbox. Changing the differential to a bigger torsen model caused it to actually underread by about 10%. I did get used to it quickly though.
In germany most people just drive at least 10% above the speed limit because of techometer inaccuracy and the tolerance of speedtraps.. If you're driving exactly 100 on a normal road people will pile up behind you pretty fast unless they can overtake. 😁My 2021 Focus ST is about 5km/h off at 100km/h, gps displays 100 when the dash shows 104-105.
I'm German too and usually overtake with exactly 5km/h over the limit when I'm driving with GPS. It's surprisingly useful in 130 roads where people stick exactly to the limit. I may not be overtaking fast but I only have 1 or 2 people tailgating me at best 😆
Does that mean normal Focus drivers in Germany routinely go at least 115kph? (105+10%) Will insurance cover damage to their own car if they have a crash no matter the speed or is there a cutoff? (say 140kph)
We in the Netherlands have something called FlitsMeister. This warns for speedtraps, average speed checks and all sort of other stuff. If I do 80 (kmh, because duh) on FlitsMeister, I'm driving 84 on my speedo. At almost every speed, it's 4 or 5 off. The car I'm talking about: 2018 VW Polo 1.6TDI with manual transmission. Not my car, but still drive it every day.
I had a Golf. It showed me digitally to which speed the cruise control was set. The speedometer showed 100km/h when the cruise was set to 106. The GPS reading was 104.
Opel Astra F did over read quite a bit if you were doing the city speed limit on the speedo which is 50 kmh you would actually be going 40, and the overread grew along with the gain of speed, it showed 140 when you were actually going 120, but the overread was within the tolerance required by the law. It was a cable speedometer and this car was from 2001!!!!! Even my Audi 80 from 1989 has an electronic speedometer with an inductive sensor on the gearbox's left axle output.
Typically I found my speedos to between 5-7% out but my BMW is alarmingly accurate I think it uses gps via the nav system . My wife’s Prius was about 10% out so 70 was 63 at best , I wonder if that was deliberate
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There's a setting (accessed via the ODB2 connector) where you can set it to be an accurate reading. I suspect that one of the previous owners has adjusted this setting.
2020 Tesla Model 3 Performance speedometer reads high but not linearly... At about 50mph, it reads 52mph, at 80mph it reads 85mph! Running 19"rims with 245/35/19 Michelin Pilot Sport 4S tires. Interesting stuff...
I’ve noticed my Porsche 944 seems to be consistently 2-3mph out across the entire speedo, not a percentage. Whereas my Mini Cooper seems to be about 5% out.
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I estimate my speedometer's accuracy by comparing its reading when I pass by a speed check sign. I find it's usually 2-3 MPH higher than my actual speed, assuming all speed check cameras are accurate.
You missed a key point: If the speedo is always +10% then your cars mileage reading is wrong. When your car's odometer indicates it's travelled 100,000 miles it will have actually only covered 90,909 miles in reality. Unless it's a Mazda mx5 of course.
Most vehicles read ( sense ) the speed and distance incredibly accurately , but, they deliberately display the speed as lower than real to conform with law. So mileage with come from the accurate reading.
@@nobodyimportant7380 that's not true. They don't display the speed as lower, they display the speed as HIGHER than it really is. Secondly there are not 2 streams of information the mileage is based entirely from the speed sensor readings, so yes the mileage will be wrong like I first explained. Maybe rename yourself to "NobodyIntelligent"
@@steve0680657 oh I'm sorry, I used the wrong word by mistake. As the ECU reads the information accurately then displays it deliberately wrong, it can be seen as 2 streams of information when read at the ECU. Displaying the speed incorrectly deliberately higher than actual, will never get the manufacturers in trouble, displaying the mileage incorrectly ( higher than actual ) would have them sued as it could be used as a way for them getting out of a mileage limited warranty repair.
@@steve0680657 one in (accurate) and one out (altered) to go to display, is two streams. But if have actual ECU data to confirm what you are saying then show me, I am happy to be incorrect with evidence showing that fact.
I've got a Volvo-v70 from 1998. At lower speeds 0-50 km/h it's spot on. But when the speedo gets up to 70-130 km/h the car is roughly traveling 5-7 km/h slower
I recently realised this when bought an Audi A3. Overreading with the 17 inch wheels. I put on 19 inches from the rs3 and the Speedo is almost spot on, 1kmh off instead of 5-6 that it was. My guess is that the manufacturer will do one speed Reading system for that particular car and will do it more accurately for the top performing version of that car as it will likely have bigger wheels. Otherwise if done in reverse it will under read in the performance trim.
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@@slowanddeliberate6893 our cops do the job in an ever older fashioned way: follow you and keep the same speed with you and hit the record button on their speedometer It is also required by law for them to turn on the red strobe light when doing this. So if your situation awareness skill is good enough you can just hit the brakes when you spot a cop following you and you'll be good to go. But most people get caught in a so called mouse trap: a hidden radar and pull you over later
My BMW was off compared to GPS and a Speed Check sign put up by the cops. My new Chevy and old Honda are dead on every time. Maybe the same German engineers that design their crappy engines design the speedo? Maybe instead of a single reading from the transmission output shaft and simple math, they over engineer it by using a dozen sensors, chains, belts, plastic guides, etc. then process it using multiple DSPs?
Here in Italy the regulation states that speedometers have to overread by at least 4km/h, with a maximum of +10%. My car is a Hyundai Tucson 2016, and testing it I found out that it overreads by exactly 4km/h consistently, when going over 40. Speed traps also have a tolerance of 10% (some sources say 15% but it's better to be on the safe side), so it's pretty easy to calculate that on a highway I can go at 143km/h, so in my car at an indicated 147km/h. Easy enough to calculate! I usually keep a GPS speedometer on my phone that tells me the average speed, so I can speed up a bit for fun when the road is empty, and still stay under 143 on average.
It's also in the auto makers best interest to over clock your speedometer as it also over clocks your odometer. This makes your vehicle warranty expire sooner. As both are calculated from wheel rotation. So at a 60k mile warranty, your warranty will expire at 58,824 miles with just a 2% over clock (70 MPH GPS reading 71.4 MPH on speedometer).
My last car was a Chevy Sonic, and I remember that I felt the speed sensation was a little off, so I checked with my phone and it was 10km/h less than speedometer's velocity.
In Germany, cars fail their biennial technical inspection (TÜV) if the speedo reads under. It can read up to 10% plus 4kph over tho. So it is usually adjusted 3-5% over (showing 103-105kph when the car is really doing 100) so that even if it‘s warmer during the inspection (=> more tyre pressure => bigger diameter = car goes further per rev => higher real speed) or something like that, it definitely won‘t read under, since failing the inspection means the car has to stay at the garage until the next possible appointment and it will cost another good 100€. No garage wants to have to tell their customer those news.
Even older cars used to overread, like 90s Opel/Vauxhalls used to have a 10% overreading - driving at 70 mph meant you're actually driving 7 miles slower. And this was not just a malfunction or bad design, it was actually to make driving safer and save drivers from speeding tickets too. It's known people like to drive fast, so car manufacturers decided to make some of their speedometers to overread alot - cuz when the driver sees a bigger number on the speedo, he assumes hes driving that fast, and that way he's satisfied while hes actually driving slower.
I once bought a used motorcycle 5h away, rode back on it. it took me a little while to realize the speedo was completely off, undereading by at least 30kmh, I was around 110kmh and passing all the traffic. My hands and butt going numb were not lying though, measuring the vibrations of the big 650cc single doing 140-150. I was slightly relieved to see that doing more reasonable speeds wasn't as uncomfortable.
This is absolutely true!! I own a 2014 Cayenne GTS and a 2018 Macan S and BOTH Read exactly 5MPH over. I asked Porsche about and they told me all their cars do this. My mom’s 2018 Audi Q5 equipped with 20” wheels is almost spot on accurate but my 2009 E63 AMG was about 3MPH over.
Have a 2002 subaru liberty and it used to overread by about 5% on factory rims. So bought bigger rims and low profile tyres. Because of the adjustment it now reads spot on with gps 👌
My 1988 Nissan Sunny has quite the tolerance, 140km/h on the speedo is 123km/h on waze, 60km/h on the speedo is 52 on waze... Reason being, some idiot put tiny wheels on the car before I bought it, should get different wheels and tires, but that'd be more expensive then the car itself, and it has new tires already
I'm in the USA. My VW id4 is +1mph, but my e90 BMW 3 series is interesting. It is +2.5mph on the speedo, but I turned on the the digital display without a "correction" and it is spot on.
Even changing tires can make a differece. You can adjust that through a tuner box though. I put larger tires on my Jeep and used my tuner to tell it how tall the tires are. My GPS and speedometer are actually very close.
Two completely different Ford vehicles, a 2014 Cmax plug-in hybrid and a 2016 F150 with 4WD, they both have the same error from actual speed versus both GPS and radar (which both agree). There's a static deviation of about one mile per hour, plus a very slight proportional deviation. To go an actual 40mph, I have the speedo at 41. To go an actual 70mph, I put the speedo (and cruise control, etc) on 72. Strange that it's the same with such different vehicles and drivetrains -- makes it seem intentional.
There are also the cars that have two speed readings, one for the ECU ( accurate ) and one for the speedo display ( showing higher speed ). General GPS is accurate to 10m at best, I am not aware of any publicly available GPS with better accuracy, Hence the reason many young drivers have been accused of speeding with their insurance black box, because they were on a Dual carriage way which was alongside and parallel to a 30mph limited local road. The GPS was showing them as on the 30MPH local road.
Two true stories that both made the news regarding speed cameras in Virginia. First was a guy that got sent a ticket with a picture of his tag and a pic of the windshield view. He sent in a picture of the money. Someone at the office sent him a pic of handcuffs. Second story was a congressman getting sent a ticket but the wife opened it and the guys side piece was clearly seen in the passenger seat when he was supposed to be out of town. He complained and that ended the speed cameras on I66 inside the Beltway. Thanks Congress guy as I drive there a lot.
Inflates everything. 10,000 miles between servicing is actually a lot less MPG or even how many miles per tank seems a lot better than it actually is… Tyres “last” longer etc
It’s mostly for safety. There’s agreement with Manufactures and regulators on the limits on how manufacturers can overate or under rate the speedo reading when leaving the factory. Depends on what kind of vehicle, the values they deem will contribute to safety. Say suvs and normal cars won’t be accurate but expect performance cars will have an accurate reading. I read you can actual request the factory/dealer to calibrate to the let the speedo read normally. Depends on the local regulations as well. And by the common speed sensors now measure the rotation on the hub. It doesn’t matter the size of Tyres and wheels. The sensor is at the hub not on the wheels. It’s rotation is constant. It controls your brakes and traction control so they should be 100% accurate in reading the speed. The ecu will read them accurate always. The ecu then just controls what you see in your speed displayed in your speedometer.
2016 Mazda CX5 Sport (USA Version). The speedo always reads like 1 or 2 mph faster than Waze. Dealer technician told me the car does this to be in compliance with certain laws. In NY the speedo must read at least as fast as the car is actually moving but can't be over by more than 10% so manufacturers intentionally calibrate the speedo to read like 1 or 2 mph faster all the time. If not they could be fined for manufacturing your car with an "unlawful speedometer".
In Australia, the car manufacturers were allowed the same 10% discrepancy. And back before say 1995, most Australian built cars had the worm drive for the speedo connected to the Gearbox. So not sure how that affects the accuracy. My speedo in KMH is roughly 3 KMH overspeed. So I know I can sit right on the speed limit of say 100 KMH and know my speedo is actually reading 97 KMH. My car was built in 2001.
2005 Subaru Impreza STI imported from Japan. Even though the speedo's been converted to indicate MPH instead of KPH it's still extremely accurate and agrees with the GPS exactly
BMWs E9x series know exactly how fast you are going, and then add an offset, whereas the older E46 series was dead on. You can actually turn it off for the digital readout, but fixing the gauge is more difficult. I read that it is due to TUV regulation requiring that is doesn't under-read even if slightly over-sized tyres are fitted.
I'm convinced it's so the odometer is fast and the warranty ends quicker. Your speedo may be way off, but plug into the onboard diagnostics and you'll find they are pretty bang on and they are both getting info from the same sensors!
Every car I have had has over read. Most read +3-5mph above the true speed all the way round the clock. While others appear to be a percentage over all the way round the clock. 1 car I had is 5mph undreread all the way round the clock. It was a 2002 vw polo
Infiniti here in the USA, with factory correct tires and wheels, will read about 3% over GPS speed reading. I re-calibrated mine with slightly larger tires.
I already know this because in my country there are some electronic boards that shows speed when your car is travelling on the highway, it's usually 4-5 kilometers less than car reading.
I have checked many cars on this. A D40 Nissan Navara used to read about 10% over up to about 70mph, so 33mph indicated was 30 actual speed and 66 indicated was actually 60. My D23/NP300 Navara read 5mph over all the time. My new Discovery reads 3mph over. My Mum had a Hyundai ix20 that used to read about 2mph over.
Found this out when I was driving down the high way side by side with my cousin while we were on the phone together and I told him to set the cruise control to 75 mph so we both set it and next thing you know he starts leaving me behind, did a bit of research and I found out that North American cars don’t do this while most other places do
Had a 2015 Mini Cooper S and it was just like your VW. Have now a 21 Hyundai Elantra N line and it is spot on with all the radar gun signs. Or with the photo radar van.
In France the camera tolerance is 5km/h, and my Polo under reads by 5km/h. So I can safely drive 10km/h higher without getting a ticket. Even for mobile and police-operated cameras, they will only fine you and remove a point if you go more than 5km/h over the limit
10mph is really extreme, ive seen it for years on different cars and the deviation is usually 4-5 km/h on standard tires, and here in Germany if you change the circumference of the tires you need to recalibrate the speedometer in order to pass TÜV inspection. My mini cooper s r53 has 4kmh deviation, other cars tested are golf 3, golf 4, volvo V40 all in the same range, GPS and speed trap tested
In my country there are sometimes speedtraps that don't ticket you, but instead display your speed. So there will be a sign saying "You are going 50 km/h" followed by a smiling or a frowning smilie depending on whether you are too fast or within the speed limit. I always use these to check how much my speedometer is lying to me, it is usually around around 5-8 km/h higher than my actual speed. Depending on the speed i am going at, 5kmh at 50 and 8kmh at 100. My country has a 4% tollerance in speed traps, however tickets are only given when more than 10km/h above the speed limit. So i usually go speedlimit + 10km/h and never gotten any tickets with that
I had a 2011 Holden Commodore SS-V In the settings menu was a tyre size section, if you put bigger wheels on you can enter the size of the tyre to allow the computer to re-calibrate the speedo.
They also take in consideration that there is an +/- 5% rolling circumference allowance, for direct electronic speedometers. In this day and age IF they really wanted, they could use the cars internal GPS to regularly re-calibrate the sensor speed off-set when say a minimum of 4 or 5 sat's are available, automatically correcting for wheel set differences and wear. Then display 2% more than the calibrated value just for the legal sake of never displaying lower than true.
1 thing that works out well with wheel speed sensors, unless the sensor system can take wheelspin into account for mileage, is if you do lots of burnouts it'll age your mileage faster than no slip, which is fair enough really!
In Australia the Design Regulation 18/03 specify for cars: _The production shall be deemed to conform to this Regulation if the following relationship between the speed indicated on the display of the speedometer (V1) and the actual speed (V2) is observed: In the case of vehicles of categories M and N:_ (Cars are in class M) 0 ≤ (V1 - V2) ≤ 0.1 V2 + 6 km/h So in short the speedo can read up to, 10%+6kph over the actual speed, but not under at all. My Honda bike is a consistent 10% higher than actual, my old Toyota also over read, but my Jeep is reasonably accurate from factory. (It is more so now that I recalibrated it against GPS via OBD2 by updating the wheel size recorded in which ever one of the computers stores that data.)
My 2017 Kia Sportage SX-T (US market) is accurate within 1~2 MPH - regardless of the actual speed driven. I have checked it against the speed readout in Google Maps, the GPS based speedometer in my radar detector, and free-standing radar speed cautions. As you noted i the video, in the US market the rules on this is within roughly 2.5% in either direction.
I live in Germany. My car reads some 10km/h off at high speed, 5km/h up to 120 km/h and it is very accurate up to 30-40 kmh. I usually drive 23 over the limit. I might still get a ticket, but I am not risking my licence (licence gets suspended from 23km/h upwards). Needless to say I do this on highways and not in cities where such high speed can be dangerous in 30km/h zones(although in some is perfectly fine).
The car I did my test in - fiat Siecento - over read by 10 mph...going round on my test knowing I was doing 20mph because the satnav said the gps speed but not going quicker otherwise my cars speedo would say I was speeding was almost painful! Interestingly one time I put larger sidewall tyres on the car and the speedo became almost perfect. I knew the difference wold be less but it was spot on at 70mph! the rpms sat lower as well so it was much more comfortable for distance :)
Having owned/driven multiple Mazdas i can confirm that all of them where almost spot on (often only 1-2kph slower at 100kph) with the speedo compared to GPS, where many german cars, even recent ones, needed a bit over 110kph on the speedo for real 100kph gps. a golf 6 i could drive at 150kph indicated on the autobahn while only doing ~132-133 real. that might also explain the tendency of many people bragging their car goes 30kph faster than the manual says (no car will do that) because simply the speedo is indicating 10% + 5kph too much and there was a slight tailwind.
My 2012 Honda Civic reads pretty accurately. I've noticed that if I'm indicating 70 on the speedometer, the GPS usually indicates within 1 mile an hour. I'm on super cheap Douglas tires from Walmart that are probably well past due for a rotation.
On BMW's (I have no knowledge regarding other brands) you're able to go into the vehicle settings using the OBD2 connection, and set your speedometer to normal or a more accurate reading.
I tested this many times on my 2005 Focus. So at the city speed limit here - 50km/h I am usually at around 55-57 on the car. But the faster I go the bigger the difference. So let's say on a highway the limit is 130km/h. On Google maps if it says 130, my car is above 140. I tested this in Germany at even higher speeds and the difference still grows.
Here in the UK our cameras have a 10% +2mph tolerance. I use waze which shows you're travelling speed. In a national 70mph I set my speed limiter at 81mph. Actual GPS speed is 77mph. Could push it a few mph more but 10% is fine. Been through mobile speed traps and average cameras like this many time never had an issue. Oh and it's a 2021 skoda fabia tsi.
I've actually been in a car that had a perfectly accurate speedometer. My old work van with brand new winter tires read exactly 80kmh while GPS said i was going 80kmh. It just comes down to tire wear and speedo calibration mainly, i think.
I've had two cars that read under, granted they were older cars without abs and traction control. One would read spot on under 20 mph, but would read 5 mph under up to 80 mph. Any faster and the speedo would be even lower. The other car would read under consistently about 2 mph under. My newest car reads pretty spot on, only being over by about 0.5 mph. Neither of the older cars was a big deal here in America where the speed of traffic dictates how fast you go more than the speed limit.
A lot of cars where you can get multiple different wheel sizes, like the golf and GTI, will set the speedometer to read perfectly for only one of wheel sizes available. This can throw off speedometers a little
Legitimately one of the first things I do when I get a new car (well, new to me) is check the speedo against my phone GPS to get an idea how the actual speed compares. In my '98 firefly the speedo overread by about 5%, but around a year before selling it I acquired a set of 14 inch wheels (as opposed to the stock 13s), which I measured the outside of the tires to be about 5% larger circumference than the 13s, and sure enough the speedo was roughly spot on running those wheels. My '93 civic also overread by around 5% if I recall. My '06 Swift is I believe 1-2% over.
This is definitely a regional related issue. In Europe and all the British colonies I have noticed that the majority of vehicles I have driven do have speedometers that display a speed that is too high. I have also found that the amount they read high is not a simple percentage as you would expect but they have a strange non linearity at a very low speed and then add a fixed speed offset. I owned one car which displayed 5km/hr too high from about 25km/hr up to way over the legal speed. Here in the USA I have owned about 8 vehicles of different makes and models and they have all had speedometers that are accurate to the nearest mph.
Now that is something to think about since we live in u s. We both like vans due to the usefulness of these vehicles. My wife drives a 03 dodge caravan. She constintly get passed and she just gets flustered. I'm going to give this concept to her and see if it's her speedo is reading correctly or her tires are properly good. Me personally I just enjoy driving. Now between semis I just try to get out of that mess. You never know.
Where I'm from, it's required by law for the speedo to overstate the speed - reason being that you couldn't ever argue you were over the limit because your speedo indicated incorrectly. Speedo has to read actual speed + (0-10)%+ 4kmph. That way you could be doing 100km/h but your speedo could read 114km/h and it would be fine. The 0-10% is to account for tyre wear, inflation of the tyre, load etc.
Right, let me know! Set your cruise control to 70mph in your car, and let me know what your phone reads! Also, let us know what car you have!
My Volvo v50 is spot on waze goes between 70 and 71
What is the point of this video? People have known about this for years and years.
My Audi A7 (2015) is usually spot on or only off by 1mph. I used to have an Audi A6 (also 2015) and that was off by 2-3mph.
@@davidt8087 What is the point of your life ? We already have billions of people and you can't provide anything the other billions won't. Replicate whatever answer you choose for yourself to the question you asked.
I remember a few years ago, where a group of taxi drivers mounted illegally small tyres on their cars, so that the system would overcharge the customer, since it relied on the car's speed to calculate distance driven.
actually, as a delivery man, i'm quite familiar with this system here in Hungary. our fiats overread by around 6km/h, and fixed cameras have a given tolerance (by law) depending on speed, in 50km/h areas its 62km/h. so in theory you could pass the camera in a 50 zone at 67, and not get a ticket. I usually play it safe as you say in the video, and never exceed 60. and it's working, I haven't gotten any tickets so far. at least not from fixed cameras.
I stick to the 10% rule.. if Im supposed to go 50 Im going 55 on the speedometer and so on. But when I go through a route that I know very well (where the straights are, where it is possible to safely ovetake, where the holes are in the road, where the cops like to measure the speed etc.), I will push the car. Theres no reason to go 90 on a road that I can perfectly travel at 150 without endangering myself nor anyone else and also without the risk of getting a ticket.
@@alunesh12345 Off point, but yes. Is speeding a sin though? I'd say it is.
@@MisoElEven If something changes you're going an extra 60kmh faster though. And what if someone doesnt realise you're going that much faster and pulls out in front of you?
@@Noreceipts400 Theres nothing that can change on that particular road and I can see several km ahead..the faster the overtaking manouver is over the safer it is. What if the driver doesnt see you when youre going the legal 90km/h while the other one is doing 80? Nothing changes, you will crash if he moves to that lane or a car flies into my face from the other side. Seriously, unless the car in front explodes theres nothing that can happen on that particular road. Lets not forget theres not much traffic anyway. If anything I would be more afraid of gypsies crossing the road with their tons of copper and other scrap metal etc. XD in the city where I was born (Košice) theyre aparently going to lower the speed limit on the highway from 130 to 90 and install traffic lights just so they can move the trash they have stolen from one side to the other because if we built a wall again then the EU could sanction us for racism/segregation. Thankfully I dont have to ride through that piece of road anymore.
Edit: also you always have to let the car in the left lane go, even if its speeding and youre just moving to the left to avoid a colission with lets say a bus.
@@alunesh12345 leave it out
wheel speed sensors are usually used for abs and esc. 99% of the time most cars use a speed sensor from the gearbox for the speedo. just FYI. Also the faster you go the futher out your speedo will read
Glad to see someone here actually knows the truth lol
Unless you have an old VW beetle with a hub reading
Lincoln mark 8 uses wheel speed sensor. I was suprised to see that my speedo worked after i swaped trannys
All the cars I have owned show speedo is off by the same absolute amount regardless of speed. The computer reads the speed from sensors and subtracts a given amount…50kph is really 46, 100 is really 96. 120 is really 116. Not a percentage amount, but a fixed amount regardless of speed.
Except most japanese cars? Which use the wheel speed sensor in the wheel hub.
You've missed out a very important part here. Your speedo might be lying, but the car's speed sensor is usually very accurate. Hook a reader up to your car's diagnostic port and access the output from the speed sensor and you will find it is usually very close to the GPS readout (also proving that the speedo is being artificially set to over estimate speed).
The whole thing with the speedo over estimating your speed in the UK and Europe is because there are significant fines for manufacturers that issue a speedo that reads a lower speed than the car is actually doing. They don't do it to protect you from speed cameras/limits; they do it to protect themselves.
As a slight aside, cars over estimating speed by significant values is not really a good thing, especially if you have a driver that doesn't understand their speedo isn't accurate. A lot of people get this idea that because their speedo says they are doing the speed limit, anybody passing them is speeding. This in turn leads to certain drivers taking it upon themselves to attempt to control other drivers speed. Or you end up with drivers angry at the people they perceive to be speeding, or angry drivers being held up by drivers who are going dangerously below the speed limit.
Vehicle technology allows for highly accurate speedo readouts. Let's stop this pandering to manufacturers, pretending that over reporting speed is a good, or even acceptable state. If Mazda can confidently set their speedos to report very close to the correct speed, none of the other main manufacturers have any excuse.
Honestly Mazda is doing a lot of things differently to other manufacturers.. while VW and its brands went the way of 1.0 3 cylinder engines with a turbo (for the low and mid end cars, you can still get a 2l min something more expensive), you have to turn all the assists off every time you start the car, many of them are quite understeery and heavy. Mazda went with 2.0-2.5l 4 cylinder atmospheric engines even for its base models, push one button and all the lane keep etc. shit assists are off until you turn them on again yourself. In Mazda you dont need an automatic gearbox to get 4x4..Even the whole infotainment is done completely differently to the whole industry.. all car manufacturers talk about how its impossible to make "good old cars" anymore while its somehow possible for Mazda. Im not saying their cars are perfect, driving a car with no turbo after driving with it for a while will feel a bit slow but the nice throttle adjustment mid corner is something I personally cant let go of.
From that I would assume that overestimating the speed is just a safe bet, simpler and possibly cheaper way to do it..just like with small turbo engines and everything else. Maybe thats the one thing every manufacturer should copy. It would certainly made roads safer if I didnt have to pass moms in their SUVs when theyre doing 40km/h all the time.
@@MisoElEven Something that could be interesting to note about the choice of engines for given market are the taxes.
In many country (including in Belgium where i live), you have a yearly taxe to pay depending on your engine displacement.
So people tend to go for smaller engines with turbo in order to pay less. And Belgium is quite expensive in that area (More than France).
Which could explain why i don't see a lot of Mazda on the road in Belgium.
That is very interesting. That means the over read could be a constant and not linear with speed.
So you would always be 5 kph above irrelevant of speed (appart for when you are at a stop or very slow i assume).
I used to think that if you have +5 at 100kph, you might have +10 at 200. Which would make sense if the overread is from the system inaccuracies instead of an electronic margin.
@@guilemaigre14 the over estimating being a fixed amount, or a percentage likely varies by manufacturer and how they are achieving the result. My past couple of vehicles have been a percentage difference.
For example, my current main vehicle (an older Nissan X-Trail (T30 model)) reads 33mph on the speedo when the sensor reads 30mph. The speedo reads 78mph when the speed sensor reads 70mph.
Would be quite interesting to have details from a range of makes and models to see the difference in how big the speed variance between the on-board computer and the speedo is; and how many are a percentage of speed difference Vs a set speed difference.
This is exactly right. My old Ford Ka reported insanely accurate speeds through the OBD port (+/- 0.3-0.5 km/h) but chose to move the needle less than it was reading.
In many parts of the US, speed cameras can't give automatic tickets. Making this a none issue, following the flow of traffic is generally the only thing to think about
in louisiana (where i am), often the posted limit is 35, but traffic is moving at 55, so if you do 35 you WILL cause an accident. in the US, it's ALWAYS better to follow traffic rather than the speed limit.
@@staterafukumoto in new york, the highway speeds are 55 but you won't catch a single car in the left/middle lanes going below 70. you can also be driving alongside cops doing that speed
@@staterafukumoto In Miami if youre not doing at least 85 in the left lanes which normally at 85-100mph sometimes 105 you getting yelled at with horns blazing that's including the coop excluding State boys
WA school zone cameras can send automatic tickets. I don't know of any other automatic ticket cameras tho.
In Oklahoma, the speed limits are anywhere from 60 to 80 on highways. Usually add 5-10 to that and you're safe. My wife and I were recently in Philadelphia and the 55 mph speed limit is more of a suggestion than the law. Go 70-80 or get rear ended. We learned that real quick when I was doing 60 on I-95. I learned then that even the worst drivers in Oklahoma are pretty tame.
I don't have cruise control, but a steady foot. My old ass VW Vento (Jetta 3) overreads by like 3km/h on winter tires and it's pretty much spot on with my summer setup
Yeah
When I’m doing the legal speed limit of 120km/h in my Lexus, Waze says I’m doing 114km/h, what I find interesting is that the Lexus CT is limited to 180km/h but on the speedometer I’ve reached 190km/h which with Waze is 180km/h so I almost wonder if Lexus knows by how much their speedos are of, limiting to the actual speed and not the speedometer
Yeah my ct is like that too and so is my Toyota
Probably adjusted for max error at certain tire thread depth. If you got a slightly larger in radius wheel, you could go faster
That is exactly how it works. Example: my e36 M3 is Limited to 250kmh but the limiter doesn’t kick in until 268kmh on the speedo
@@geraldkottler3014 yup, that's how it works in modern amgs as well
of course toyota know the speedo is out. in this day and age, if they wanted to, they can make speedos 99% if they want.
As another separate comment, I also want to note the effect of the wheel circumference. Back in the early 2000s both myself and my sister owned an E110 Corolla. Mine had the stock 175/65/14 wheels. Hers was modified by the previous owner to run 185/60/14. That's a difference in sidewall height of 2.75mm, or 5.5mm in circumference. On a long-haul trip from Namibia to South Africa we were driving together, and I asked her why she was driving 5km/h below the speed limit. She said she wasn't...
"modified" bruh that's just changing tires lol
@@Nibblerrare your 12? That’s exactly how the verb modify is used.
@@mahadali619 25 actually. And no, no one calls changing tires "modifying".
@@Nibblerr that’s literally what the word means, if you’ve changed something, you’ve modified it, be it tires or an engine
@@mahadali619 something tells me you've never worked on anything.
Yeah, that's why it's OK to be slightly speeding most of the time, cause you're actually not speeding at all. But I agree with the regulations - it is far more convenient to drive just a bit slower, without even noticing, than to get a ticket while thinking that the speed was under the limit.
I kinda knew this already since i noticed that gps speed is usually less than the car speed. My dilema is: what about the car odometer? If your car overreads in 99% of the cases, then that means the car odometer is higher than it should be. Also the mileage is worse than the car reports. So, if the car overreports by 5% then for a 60mpg car means 57, not a huge difference, but its a difference
For the odometer it's not particularly important because it's only a general indication rather than a datum point for specific tasks. If you were buying a second hand car a 90000 mile car that has done 85% of those miles on the motorway could be in better mechanical order than a 25000 mile car of the same age that has been used as a courtesy car and ragged every day of its life, also if you're due a service/belt change at 20K it's not likely to matter within +/-15%. Indicated mpg is again never particularly accurate, it's an estimation designed to highlight optimal engine conditions rather than an actual indicator of consumption.
From what i gathered on other comments, the odometer is usually very accurate. It is only when displaying the speed that they add a margin. Now i lack soucres to confirm, but others seems to says so.
My old passat b5 overread 10km/h but odometer showed less km. It was strange but that meant that car used less fuel than calculated or indicated😁
I can't say for all odometers of course, but I can tell you for my last couple of vehicles the odometer is not connected to the speedo output.
I have mentioned in a comment below that whilst the speedo is often quite inaccurate, the speed sensor on onboard computer monitoring speed in a vehicle is usually very accurate. If you connect to the diagnostic port on relatively modern vehicles, and check the speed sensor output, you will find it is different to the vehicle's speedo output. Odometer figures are based on using that speed sensor.
So, for example, when my vehicle's onboard computer reports the speed sensor as running at 70mph (using the EODB (equivalent of the OBD-II port used in North America) port to read data), my speedo with display 78mph. But if I was to run constantly for an hour at that speed, my odometer would increase by 70 miles.
@@damionlee7658 guess overreporting is so bad that they artificially reduce the value. I usually set my cruise control to the gps speed, sometimes 5-10km above it, but it seems really strange. Also modern cars should be able to auto adjust for wheel, since they have a gps internally and they can compare the gps speed to the wheel speed. Tesla can detect wheel uneven wear, this should be easier to do
My E39 528i is exactly 5 kmh over the real speed. The funny thing is that in the hidden menu on the bord computer there is a real speed option which is spot on but must be turned on every time you start the car if you want to use it.
My e46 touring shows exactly the same 5 km/h over the actual speed. Hidden menu is awesome
How do you turn it on? I would love to try that out on my E39.
@@xJustInTime it depends on the version of obc you have (big or small screen in the cluster) but there are a lot of tutorials on TH-cam. Normally on all BMWs it's turned on by holding the button to reset the trip odometer for around 10-20 seconds. You have to unlock it as well after you get in, so better check a TH-cam tutorial as it's a but too much to type in a comment.
Why would they lie about it in the first place?
maybe you have bigger tyres than stock
Having driven many cars both in the US and Europe, I can confirm, almost all cars consistently overread in Europe, but in USA it's much closer. I've heard carmakers do this to make the car feel "faster", as you seemingly reach a higher number sooner than if the speedo was accurate, whilst still staying within the lawful limit.
Can confirm, Mazdas are accurate even in Europe.
I learnt about this when I was still in high school, when I got my first car I already knew that 129km on my Speedo was 125km in reality but I also noticed that the accuracy varies depending on how fast you're going.
My GPS sat nav screen was always showing a few KMH over the indicated speed and it annoyed the hell out of me, so I recalibrated mine on my E46 M3 by opeing up the speedo cluster and readjusting the needle.
I've been using the 10% rule for ages. I regularly drive 10% over the speed limit while going through speed cameras and I've yet to get a ticket (other than when I've not known I'm going past a camera).
Yeah for 20 years
in maryland, where i live, the fixed speed cameras allow you to go up to 12 miles an hour over the limit, so 37 in a 25 etc... Of course most people dont know this so they slam on the brakes right at the camera and go 10 under the limit then floor it afterwards cuz idiots ...
In Australia a speedo is allowed to be 10% inaccurate. In the past most cars were fairly accurate, but that changed in 2008.
Starting in October 2008 car manufactures had to list on the windscreen of a new car its fuel consumption rating. Manufactures soon worked out that they could improve their fuel ratings by making the cars speedos inaccurate. My 2012 Subaru was so inaccurate ( 8% higher ) that I used to have a old phone sitting on my dash that I used as a GPS speedo.
No need for the GPS speedo anymore as my current Mercedes is 100% accurate. As a result my Mercedes fuel consumption reading is 100% accurate, not reduced by a false 8% like in my Subaru.
In Australia, regulations (ADR18) required a car built before July 2006 to have a speedo read the actual speed +/- 10%. The vast majority of manufacturers, of course, tried to make the speedo as accurate as possible.
In July 2006 that regulation changed, so that a speedo can NEVER read a lower speed than what the vehicle is actually doing, but MAY read up to 10% + 4km/h over the actual speed.
So not really a significant change. Except, the national transport authority in Oz ... err ... actively 'encourages' manufacturers to make maximum use of the allowed tolerance. Put simply, it is a strategy to make the speedos in all cars (made after 2006) read high, thereby slowing traffic. So the same result as reducing ALL speed limits across the country by 10% + 4km/h , without the political backlash of doing so.
And before you say "but my car here in Australia is made in Europe, so it will be more accurate", let me add a minor detail that was missed in the video. Basically all modern cars get an extremely accurate speed reading from the relevant sensor, and that is what is supplied to the ECU etc. But the ECU then hands that input to the dash display unit, which displays the speed etc. It is in this unit that the speed is 'modified' to read 10% + 4km/h higher than the actual speed. This allows for the odometer to remain accurate, as the 'correction' is not applied to that element of the display. So all the European manufacturers have to do, is a simple software update to the cars coming to Australia, to make the speedo read high, as is required.
So to put this in more practical terms. When you are in the Righthand lane of a multilane motorway, trying to overtake at the actual 110km/h speed limit, and there is a car sitting in front of you, slowing you down ... say doing 96km/h (by your accurate speedo or GPS)? Well, his speedo says he is doing 110. Just as the authorities want.
And people still complain when they get snapped by a speed camera and the speed camera even has a warning sign ahead of it lol
I got called out :D I am definitely doing the math - Waze speed readout + 5km/h tolerance on measuring equipment so in 50km/h I will be usually doing 58km/h on the speedometer and 55km/h on GPS... but I noticed the car having different margins at different speeds and that a GPS speed read-out is wrong if you are going up or down a hill -- so I have to account for that too
That’s interesting. Adds another level to how fast people drive now. Really tempted to test this out now 😂
Edit: tested the theory and yes, my dads 2018 BMW 5-Series does it too, the car was 2 mph above the what the GPS was telling me.
I used to have an E36 and I currently have an E60. Both would consistently show 2mph faster than the GPS showed I was going. The E60 is a little more odd though. I've coded the cluster to show a digital reading of the current speed. If I set my cruise to 72mph, the GPS speedometer on my phone will show 70mph, but the digital reading in my gauge cluster will show 69mph.
The only upside of living in the US is that we generally don't have average speed cams, no one knows how to drive, but the rules only matter when caught, and if you do go the speed limit on the highway you will be killed because no one else will go the speed posted.
My BMW shows 4 MPH on the speedometer over GPS speed indicators. I always suspected this was intentionally done so that the car warranty would be voided sooner than it should have otherwise been.
When I got my first car - a Honda CR-Z - a few months ago at 18, naturally I was super hesitant with my speed & I've actually been wondering ever since why Google maps reads my speed 3mph less than the car does (I assumed it was an inaccuracy on my phone's part). This video's been an awesome help, cheers!!
I've got a CR-V, and the speedo always ready at about 1.5 - 2mph faster than what google maps reads
5:11 Of course, timing for record speed attempts is generally done with external equipment (though I'm sure it's useful for the driver to have an accurate indication too!).
My Mitsubishi Eclipse GT v6 from 2008 reads 10% under. I actually noticed just because 120kmh didn’t feel remotely as fast as it did in my Santa Fe and when tested found that I was completely correct. Living in Ontario Canada, and the car has 150k clicks on it. It’s really neat to know it’s not just a my car problem
Yeah, been aware of this for more than ten years. In my Jetta, I've noticed 33 is 30mph; 44 is 40mph, 54 is 50mph and 66 is 60mph. Have driven past speed cameras hundreds of times at these speeds and not gotten a single ticket.
I have noticed that in my 2 VWs as well (Golf and Touareg) The faster I go, the more the car would over-read. Phone GPS would say 80, car might say 85
My mate and i actually figured this one out pretty recently, got a 2010 VE Holden Commodore SV6 and when the dash is spot on 110km/h, phone GPS only shows 105km/h. On a 7 hour drive in Western Australia that 5km/h does add up!!
that's a 20mn difference if you drive 100% on cruise control, less if you have some slowdowns
Yes SSC and the Tuatara.. 🤔💭301 Mph, Let Alone 331 Mph!🤥 A record run requires reliable data.. 🚗💨💨💨
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@@alunesh12345 UwU
When I got my BMW I noticed the speedometer was always reading faster than I was actually going so I researched it and apparently German cars must always over read and never under read the speed. There’s a setting in BMWs that lets you make the speedometer display the actual speed but that’s turned off in the United States. I used an online calculator to figure out what tire size I needed to install to get the true speed reading on my speedometer and installed that size of tires now. They were very close to the original size but made just a small difference in my speedometer and now it’s spot on.
Thats right. Im in europe and my BMW have submenu where you can read actual speed. It is always few km/h lower than reading speedometer is displaying.
I can tell that at least an NB MX-5 does use the sensors from a gearbox. Changing the differential to a bigger torsen model caused it to actually underread by about 10%. I did get used to it quickly though.
Congrats on 100k subscribers!🎉🎉🥳
In germany most people just drive at least 10% above the speed limit because of techometer inaccuracy and the tolerance of speedtraps.. If you're driving exactly 100 on a normal road people will pile up behind you pretty fast unless they can overtake. 😁My 2021 Focus ST is about 5km/h off at 100km/h, gps displays 100 when the dash shows 104-105.
I'm German too and usually overtake with exactly 5km/h over the limit when I'm driving with GPS. It's surprisingly useful in 130 roads where people stick exactly to the limit. I may not be overtaking fast but I only have 1 or 2 people tailgating me at best 😆
Does that mean normal Focus drivers in Germany routinely go at least 115kph? (105+10%)
Will insurance cover damage to their own car if they have a crash no matter the speed or is there a cutoff? (say 140kph)
We in the Netherlands have something called FlitsMeister. This warns for speedtraps, average speed checks and all sort of other stuff. If I do 80 (kmh, because duh) on FlitsMeister, I'm driving 84 on my speedo. At almost every speed, it's 4 or 5 off.
The car I'm talking about:
2018 VW Polo 1.6TDI with manual transmission. Not my car, but still drive it every day.
I had a Golf. It showed me digitally to which speed the cruise control was set. The speedometer showed 100km/h when the cruise was set to 106. The GPS reading was 104.
Unusual usually golfs read high
Opel Astra F did over read quite a bit if you were doing the city speed limit on the speedo which is 50 kmh you would actually be going 40, and the overread grew along with the gain of speed, it showed 140 when you were actually going 120, but the overread was within the tolerance required by the law. It was a cable speedometer and this car was from 2001!!!!! Even my Audi 80 from 1989 has an electronic speedometer with an inductive sensor on the gearbox's left axle output.
Typically I found my speedos to between 5-7% out but my BMW is alarmingly accurate I think it uses gps via the nav system . My wife’s Prius was about 10% out so 70 was 63 at best , I wonder if that was deliberate
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There's a setting (accessed via the ODB2 connector) where you can set it to be an accurate reading. I suspect that one of the previous owners has adjusted this setting.
@@alunesh12345 go away
@@igniteED No previous owners on my g82 im the first
2020 Tesla Model 3 Performance speedometer reads high but not linearly... At about 50mph, it reads 52mph, at 80mph it reads 85mph! Running 19"rims with 245/35/19 Michelin Pilot Sport 4S tires. Interesting stuff...
It's good the speedo over reads. That saved me a few times from speed cameras.
VW Touareg 2005 3.0 TDI, spot on with both 18" summer tire and 17" winters. I just love it!
I’ve noticed my Porsche 944 seems to be consistently 2-3mph out across the entire speedo, not a percentage. Whereas my Mini Cooper seems to be about 5% out.
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@@alunesh12345 this has nothing to do with cars
I estimate my speedometer's accuracy by comparing its reading when I pass by a speed check sign. I find it's usually 2-3 MPH higher than my actual speed, assuming all speed check cameras are accurate.
You missed a key point: If the speedo is always +10% then your cars mileage reading is wrong. When your car's odometer indicates it's travelled 100,000 miles it will have actually only covered 90,909 miles in reality.
Unless it's a Mazda mx5 of course.
Most vehicles read ( sense ) the speed and distance incredibly accurately , but, they deliberately display the speed as lower than real to conform with law. So mileage with come from the accurate reading.
@@nobodyimportant7380 that's not true. They don't display the speed as lower, they display the speed as HIGHER than it really is.
Secondly there are not 2 streams of information the mileage is based entirely from the speed sensor readings, so yes the mileage will be wrong like I first explained.
Maybe rename yourself to "NobodyIntelligent"
@@steve0680657 oh I'm sorry, I used the wrong word by mistake. As the ECU reads the information accurately then displays it deliberately wrong, it can be seen as 2 streams of information when read at the ECU.
Displaying the speed incorrectly deliberately higher than actual, will never get the manufacturers in trouble, displaying the mileage incorrectly ( higher than actual ) would have them sued as it could be used as a way for them getting out of a mileage limited warranty repair.
@@nobodyimportant7380 there are not 2 streams of information the mileage correlates to the speed.
@@steve0680657 one in (accurate) and one out (altered) to go to display, is two streams. But if have actual ECU data to confirm what you are saying then show me, I am happy to be incorrect with evidence showing that fact.
I've got a Volvo-v70 from 1998. At lower speeds 0-50 km/h it's spot on. But when the speedo gets up to 70-130 km/h the car is roughly traveling 5-7 km/h slower
I recently realised this when bought an Audi A3. Overreading with the 17 inch wheels. I put on 19 inches from the rs3 and the Speedo is almost spot on, 1kmh off instead of 5-6 that it was. My guess is that the manufacturer will do one speed Reading system for that particular car and will do it more accurately for the top performing version of that car as it will likely have bigger wheels. Otherwise if done in reverse it will under read in the performance trim.
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Speedo means something different here. The title just cracked me up and hearing it was hilarious. Very informative though.
Trivia: In Japan we have misdemeanor speeding (
In the US we mostly catch speeders the old fashioned way: a cop with a radar gun.
@@slowanddeliberate6893 our cops do the job in an ever older fashioned way: follow you and keep the same speed with you and hit the record button on their speedometer
It is also required by law for them to turn on the red strobe light when doing this. So if your situation awareness skill is good enough you can just hit the brakes when you spot a cop following you and you'll be good to go.
But most people get caught in a so called mouse trap: a hidden radar and pull you over later
My BMW was off compared to GPS and a Speed Check sign put up by the cops. My new Chevy and old Honda are dead on every time. Maybe the same German engineers that design their crappy engines design the speedo?
Maybe instead of a single reading from the transmission output shaft and simple math, they over engineer it by using a dozen sensors, chains, belts, plastic guides, etc. then process it using multiple DSPs?
I have a T-Cross (but in Brazil) and the speedometer reading is very spot on. Most of the times, the difference is in the scale of one kilometer.
Here in Italy the regulation states that speedometers have to overread by at least 4km/h, with a maximum of +10%. My car is a Hyundai Tucson 2016, and testing it I found out that it overreads by exactly 4km/h consistently, when going over 40.
Speed traps also have a tolerance of 10% (some sources say 15% but it's better to be on the safe side), so it's pretty easy to calculate that on a highway I can go at 143km/h, so in my car at an indicated 147km/h. Easy enough to calculate!
I usually keep a GPS speedometer on my phone that tells me the average speed, so I can speed up a bit for fun when the road is empty, and still stay under 143 on average.
It's also in the auto makers best interest to over clock your speedometer as it also over clocks your odometer. This makes your vehicle warranty expire sooner. As both are calculated from wheel rotation. So at a 60k mile warranty, your warranty will expire at 58,824 miles with just a 2% over clock (70 MPH GPS reading 71.4 MPH on speedometer).
My last car was a Chevy Sonic, and I remember that I felt the speed sensation was a little off, so I checked with my phone and it was 10km/h less than speedometer's velocity.
In Germany, cars fail their biennial technical inspection (TÜV) if the speedo reads under. It can read up to 10% plus 4kph over tho. So it is usually adjusted 3-5% over (showing 103-105kph when the car is really doing 100) so that even if it‘s warmer during the inspection (=> more tyre pressure => bigger diameter = car goes further per rev => higher real speed) or something like that, it definitely won‘t read under, since failing the inspection means the car has to stay at the garage until the next possible appointment and it will cost another good 100€. No garage wants to have to tell their customer those news.
Even older cars used to overread, like 90s Opel/Vauxhalls used to have a 10% overreading - driving at 70 mph meant you're actually driving 7 miles slower. And this was not just a malfunction or bad design, it was actually to make driving safer and save drivers from speeding tickets too. It's known people like to drive fast, so car manufacturers decided to make some of their speedometers to overread alot - cuz when the driver sees a bigger number on the speedo, he assumes hes driving that fast, and that way he's satisfied while hes actually driving slower.
I once bought a used motorcycle 5h away, rode back on it. it took me a little while to realize the speedo was completely off, undereading by at least 30kmh, I was around 110kmh and passing all the traffic.
My hands and butt going numb were not lying though, measuring the vibrations of the big 650cc single doing 140-150. I was slightly relieved to see that doing more reasonable speeds wasn't as uncomfortable.
This is absolutely true!! I own a 2014 Cayenne GTS and a 2018 Macan S and BOTH Read exactly 5MPH over. I asked Porsche about and they told me all their cars do this. My mom’s 2018 Audi Q5 equipped with 20” wheels is almost spot on accurate but my 2009 E63 AMG was about 3MPH over.
Have a 2002 subaru liberty and it used to overread by about 5% on factory rims. So bought bigger rims and low profile tyres. Because of the adjustment it now reads spot on with gps 👌
My 1988 Nissan Sunny has quite the tolerance, 140km/h on the speedo is 123km/h on waze, 60km/h on the speedo is 52 on waze... Reason being, some idiot put tiny wheels on the car before I bought it, should get different wheels and tires, but that'd be more expensive then the car itself, and it has new tires already
SPEED CAMERAS ARE BANNED WHERE I LIVE! HAHAHAHAHAHAHA
I'm in the USA. My VW id4 is +1mph, but my e90 BMW 3 series is interesting. It is +2.5mph on the speedo, but I turned on the the digital display without a "correction" and it is spot on.
Even changing tires can make a differece. You can adjust that through a tuner box though. I put larger tires on my Jeep and used my tuner to tell it how tall the tires are. My GPS and speedometer are actually very close.
Two completely different Ford vehicles, a 2014 Cmax plug-in hybrid and a 2016 F150 with 4WD, they both have the same error from actual speed versus both GPS and radar (which both agree). There's a static deviation of about one mile per hour, plus a very slight proportional deviation. To go an actual 40mph, I have the speedo at 41. To go an actual 70mph, I put the speedo (and cruise control, etc) on 72. Strange that it's the same with such different vehicles and drivetrains -- makes it seem intentional.
There are also the cars that have two speed readings, one for the ECU ( accurate ) and one for the speedo display ( showing higher speed ).
General GPS is accurate to 10m at best, I am not aware of any publicly available GPS with better accuracy, Hence the reason many young drivers have been accused of speeding with their insurance black box, because they were on a Dual carriage way which was alongside and parallel to a 30mph limited local road. The GPS was showing them as on the 30MPH local road.
Two true stories that both made the news regarding speed cameras in Virginia.
First was a guy that got sent a ticket with a picture of his tag and a pic of the windshield view. He sent in a picture of the money. Someone at the office sent him a pic of handcuffs. Second story was a congressman getting sent a ticket but the wife opened it and the guys side piece was clearly seen in the passenger seat when he was supposed to be out of town. He complained and that ended the speed cameras on I66 inside the Beltway. Thanks Congress guy as I drive there a lot.
Inflates everything.
10,000 miles between servicing is actually a lot less
MPG or even how many miles per tank seems a lot better than it actually is…
Tyres “last” longer etc
It’s mostly for safety. There’s agreement with Manufactures and regulators on the limits on how manufacturers can overate or under rate the speedo reading when leaving the factory. Depends on what kind of vehicle, the values they deem will contribute to safety. Say suvs and normal cars won’t be accurate but expect performance cars will have an accurate reading. I read you can actual request the factory/dealer to calibrate to the let the speedo read normally. Depends on the local regulations as well. And by the common speed sensors now measure the rotation on the hub. It doesn’t matter the size of Tyres and wheels. The sensor is at the hub not on the wheels. It’s rotation is constant. It controls your brakes and traction control so they should be 100% accurate in reading the speed. The ecu will read them accurate always. The ecu then just controls what you see in your speed displayed in your speedometer.
2016 Mazda CX5 Sport (USA Version). The speedo always reads like 1 or 2 mph faster than Waze. Dealer technician told me the car does this to be in compliance with certain laws. In NY the speedo must read at least as fast as the car is actually moving but can't be over by more than 10% so manufacturers intentionally calibrate the speedo to read like 1 or 2 mph faster all the time. If not they could be fined for manufacturing your car with an "unlawful speedometer".
In Australia, the car manufacturers were allowed the same 10% discrepancy. And back before say 1995, most Australian built cars had the worm drive for the speedo connected to the Gearbox. So not sure how that affects the accuracy. My speedo in KMH is roughly 3 KMH overspeed. So I know I can sit right on the speed limit of say 100 KMH and know my speedo is actually reading 97 KMH. My car was built in 2001.
2005 Subaru Impreza STI imported from Japan. Even though the speedo's been converted to indicate MPH instead of KPH it's still extremely accurate and agrees with the GPS exactly
BMWs E9x series know exactly how fast you are going, and then add an offset, whereas the older E46 series was dead on. You can actually turn it off for the digital readout, but fixing the gauge is more difficult. I read that it is due to TUV regulation requiring that is doesn't under-read even if slightly over-sized tyres are fitted.
In the US, 2015 Volvo XC60 says 70 MPH while gps says 72 MPH.
I'm convinced it's so the odometer is fast and the warranty ends quicker. Your speedo may be way off, but plug into the onboard diagnostics and you'll find they are pretty bang on and they are both getting info from the same sensors!
Every car I have had has over read. Most read +3-5mph above the true speed all the way round the clock. While others appear to be a percentage over all the way round the clock. 1 car I had is 5mph undreread all the way round the clock. It was a 2002 vw polo
Infiniti here in the USA, with factory correct tires and wheels, will read about 3% over GPS speed reading. I re-calibrated mine with slightly larger tires.
I already know this because in my country there are some electronic boards that shows speed when your car is travelling on the highway, it's usually 4-5 kilometers less than car reading.
I have checked many cars on this. A D40 Nissan Navara used to read about 10% over up to about 70mph, so 33mph indicated was 30 actual speed and 66 indicated was actually 60. My D23/NP300 Navara read 5mph over all the time. My new Discovery reads 3mph over. My Mum had a Hyundai ix20 that used to read about 2mph over.
Found this out when I was driving down the high way side by side with my cousin while we were on the phone together and I told him to set the cruise control to 75 mph so we both set it and next thing you know he starts leaving me behind, did a bit of research and I found out that North American cars don’t do this while most other places do
Had a 2015 Mini Cooper S and it was just like your VW. Have now a 21 Hyundai Elantra N line and it is spot on with all the radar gun signs. Or with the photo radar van.
Our -17 Mazda 6 over reads by like 2km/h when going 80, which I find really accurate!
In France the camera tolerance is 5km/h, and my Polo under reads by 5km/h. So I can safely drive 10km/h higher without getting a ticket. Even for mobile and police-operated cameras, they will only fine you and remove a point if you go more than 5km/h over the limit
10mph is really extreme, ive seen it for years on different cars and the deviation is usually 4-5 km/h on standard tires, and here in Germany if you change the circumference of the tires you need to recalibrate the speedometer in order to pass TÜV inspection. My mini cooper s r53 has 4kmh deviation, other cars tested are golf 3, golf 4, volvo V40 all in the same range, GPS and speed trap tested
50€ on the dashboard and any car will pass :D
@@MisoElEven XD I'd love to know where that is, would have saved me around 700€ last month for the inspection lol
In my country there are sometimes speedtraps that don't ticket you, but instead display your speed. So there will be a sign saying "You are going 50 km/h" followed by a smiling or a frowning smilie depending on whether you are too fast or within the speed limit. I always use these to check how much my speedometer is lying to me, it is usually around around 5-8 km/h higher than my actual speed. Depending on the speed i am going at, 5kmh at 50 and 8kmh at 100.
My country has a 4% tollerance in speed traps, however tickets are only given when more than 10km/h above the speed limit. So i usually go speedlimit + 10km/h and never gotten any tickets with that
I had a 2011 Holden Commodore SS-V In the settings menu was a tyre size section, if you put bigger wheels on you can enter the size of the tyre to allow the computer to re-calibrate the speedo.
They also take in consideration that there is an +/- 5% rolling circumference allowance, for direct electronic speedometers. In this day and age IF they really wanted, they could use the cars internal GPS to regularly re-calibrate the sensor speed off-set when say a minimum of 4 or 5 sat's are available, automatically correcting for wheel set differences and wear. Then display 2% more than the calibrated value just for the legal sake of never displaying lower than true.
1 thing that works out well with wheel speed sensors, unless the sensor system can take wheelspin into account for mileage, is if you do lots of burnouts it'll age your mileage faster than no slip, which is fair enough really!
In Australia the Design Regulation 18/03 specify for cars:
_The production shall be deemed to conform to this Regulation if the following relationship between the speed indicated on the display of the speedometer (V1) and the actual speed (V2) is observed:
In the case of vehicles of categories M and N:_ (Cars are in class M)
0 ≤ (V1 - V2) ≤ 0.1 V2 + 6 km/h
So in short the speedo can read up to, 10%+6kph over the actual speed, but not under at all.
My Honda bike is a consistent 10% higher than actual, my old Toyota also over read, but my Jeep is reasonably accurate from factory. (It is more so now that I recalibrated it against GPS via OBD2 by updating the wheel size recorded in which ever one of the computers stores that data.)
My 2017 Kia Sportage SX-T (US market) is accurate within 1~2 MPH - regardless of the actual speed driven. I have checked it against the speed readout in Google Maps, the GPS based speedometer in my radar detector, and free-standing radar speed cautions.
As you noted i the video, in the US market the rules on this is within roughly 2.5% in either direction.
I live in Germany. My car reads some 10km/h off at high speed, 5km/h up to 120 km/h and it is very accurate up to 30-40 kmh. I usually drive 23 over the limit. I might still get a ticket, but I am not risking my licence (licence gets suspended from 23km/h upwards). Needless to say I do this on highways and not in cities where such high speed can be dangerous in 30km/h zones(although in some is perfectly fine).
The car I did my test in - fiat Siecento - over read by 10 mph...going round on my test knowing I was doing 20mph because the satnav said the gps speed but not going quicker otherwise my cars speedo would say I was speeding was almost painful!
Interestingly one time I put larger sidewall tyres on the car and the speedo became almost perfect. I knew the difference wold be less but it was spot on at 70mph! the rpms sat lower as well so it was much more comfortable for distance :)
Having owned/driven multiple Mazdas i can confirm that all of them where almost spot on (often only 1-2kph slower at 100kph) with the speedo compared to GPS, where many german cars, even recent ones, needed a bit over 110kph on the speedo for real 100kph gps. a golf 6 i could drive at 150kph indicated on the autobahn while only doing ~132-133 real.
that might also explain the tendency of many people bragging their car goes 30kph faster than the manual says (no car will do that) because simply the speedo is indicating 10% + 5kph too much and there was a slight tailwind.
My 2012 Honda Civic reads pretty accurately. I've noticed that if I'm indicating 70 on the speedometer, the GPS usually indicates within 1 mile an hour. I'm on super cheap Douglas tires from Walmart that are probably well past due for a rotation.
On BMW's (I have no knowledge regarding other brands) you're able to go into the vehicle settings using the OBD2 connection, and set your speedometer to normal or a more accurate reading.
I tested this many times on my 2005 Focus. So at the city speed limit here - 50km/h I am usually at around 55-57 on the car. But the faster I go the bigger the difference. So let's say on a highway the limit is 130km/h. On Google maps if it says 130, my car is above 140. I tested this in Germany at even higher speeds and the difference still grows.
Here in the UK our cameras have a 10% +2mph tolerance.
I use waze which shows you're travelling speed. In a national 70mph I set my speed limiter at 81mph. Actual GPS speed is 77mph. Could push it a few mph more but 10% is fine.
Been through mobile speed traps and average cameras like this many time never had an issue.
Oh and it's a 2021 skoda fabia tsi.
I've actually been in a car that had a perfectly accurate speedometer. My old work van with brand new winter tires read exactly 80kmh while GPS said i was going 80kmh.
It just comes down to tire wear and speedo calibration mainly, i think.
My 2006 honda accord is spot on with most of the apps, and almost all the electronic speed bumbs with wires on the floor to get the measurements
I've had two cars that read under, granted they were older cars without abs and traction control. One would read spot on under 20 mph, but would read 5 mph under up to 80 mph. Any faster and the speedo would be even lower. The other car would read under consistently about 2 mph under. My newest car reads pretty spot on, only being over by about 0.5 mph. Neither of the older cars was a big deal here in America where the speed of traffic dictates how fast you go more than the speed limit.
A lot of cars where you can get multiple different wheel sizes, like the golf and GTI, will set the speedometer to read perfectly for only one of wheel sizes available. This can throw off speedometers a little
Legitimately one of the first things I do when I get a new car (well, new to me) is check the speedo against my phone GPS to get an idea how the actual speed compares. In my '98 firefly the speedo overread by about 5%, but around a year before selling it I acquired a set of 14 inch wheels (as opposed to the stock 13s), which I measured the outside of the tires to be about 5% larger circumference than the 13s, and sure enough the speedo was roughly spot on running those wheels.
My '93 civic also overread by around 5% if I recall.
My '06 Swift is I believe 1-2% over.
This is definitely a regional related issue. In Europe and all the British colonies I have noticed that the majority of vehicles I have driven do have speedometers that display a speed that is too high. I have also found that the amount they read high is not a simple percentage as you would expect but they have a strange non linearity at a very low speed and then add a fixed speed offset. I owned one car which displayed 5km/hr too high from about 25km/hr up to way over the legal speed.
Here in the USA I have owned about 8 vehicles of different makes and models and they have all had speedometers that are accurate to the nearest mph.
Now that is something to think about since we live in u s. We both like vans due to the usefulness of these vehicles. My wife drives a 03 dodge caravan. She constintly get passed and she just gets flustered. I'm going to give this concept to her and see if it's her speedo is reading correctly or her tires are properly good. Me personally I just enjoy driving. Now between semis I just try to get out of that mess. You never know.
Where I'm from, it's required by law for the speedo to overstate the speed - reason being that you couldn't ever argue you were over the limit because your speedo indicated incorrectly. Speedo has to read actual speed + (0-10)%+ 4kmph. That way you could be doing 100km/h but your speedo could read 114km/h and it would be fine. The 0-10% is to account for tyre wear, inflation of the tyre, load etc.