Difference between your car speedometer and GPS speed

Here we test the speedometer on Google maps and compare it with the speed reported by an Audi, as you can see there is a difference between real speed and reported speed

[vindowswista]

GPS is very accurate. Tested it. I used HUD, phone and road radar that shows my speed - all these three reports 57 km/h while car speedometer was set at 65 km/h (cruise control).

[miked]

The other thing you need to consider is the coefficient of friction between the wheel in the road. It changes with temperature, rain, ice/snow, sand on the road, cement, or asphalt...etc. The more the tire slips, the more engine hp and rpm you need to maintain the same speed. So if your gps speed is 50 and your speedometer speed is 57, your theoretical coefficient of friction is 0.877.

[mohammedkhan]

Just drove 37mph in a 30mph road my car dash is digital there was a police mobile camera speed van parked on the road worried about points on my licence and now viewing your video for help 😂😂

[FishySituation]

It's basically the same in most countries. I use the Incitatio app on my phone as a digital speedometer. It's also fun to test acceleration with the same app on the diffenret rentals I drive.

[robinsattahip]

Yes, I've noticed the same thing on a Toyota Yaris in Asia. I thought the GPS was off.

[GregoryMichaelSuto]

Digital speedometers are as of now more accurate than gps speedometers. The gps can not compensate for the time it takes for the signal to go to and from the satellite and then back to give a speed reading based on the amount of time it takes a car to get from a single point to another. Kind of like a tv network signal reaching peoples television receivers at different times causing a lag for the ones farthest away. A digital speedometer that is built into the car simply determines the cars speed based on tire rotations in a period of time. The cars tire size has to be considered for this. If you change your tire size your digital speedometer will be off. You might be going slower if you changed your tire to a smaller size. Even a police speed detector is going to be less accurate than a digital speedometer built into the car. The radar can not compensate for the time it takes the signal to go to and from the car.

[CatalinDumitriu]

The difference between speedometer and google maps is somewhere at 5miles at 70m/h. So basically speedometer at 70(cruise control) and gps shows 65 or 66 m/h

[kjni]

I have been told that speed indicated on the car is always faster then gps because if indicated lower and you thought you were at 70mph you could be doing a higher speed and might get a ticket.

[ddemaine]

Another way to test, is see how many seconds it takes to do a mile ("n"). What you then do is divide 3600 by n to get your true mph.

[By.ozalsa]

In my own experience all car brands’ speedos above 100km/h speed produce a difference of roughly 5 k /h, with an exception to German ones, (Porsche, BMW…). I feel it’s to do with calibration of the speedos.

[taseensoomro]

Great video. Thanks for demonstration.

[synckid]

Just on a note trucks actually have deadly speedometers same as GPS tested.

[TMCHL]

My difference was about 4miles slower on gps but now changed alloys from 225/45/17 to 18 difference gone down to 2mph so be careful about the tyre and wheel size…I rather keep the same 45 profile tyres not 40 speedo reading is effected 2mph up to 50 (50 is actually 52) and 3mph over 50 (I.e 70 is actually 73mph)

[jackulaoutdoors]

Noticed this today in my Kia Rio.
I was doing 50 in the car but on gps I was only 46...

Theres a speed camera near my home in a 40 area I have gone past it a few times at 45-48 and never got a ticket.
Today I went at 48 miles an hour in the car and the gps said 42 so I'm wondering if this is why I've never got a ticket

[bb]

My car shows a 10% difference in speed to the speedometer on my phone

[MaseraSteve]

I'm a little bit skeptical of solely gps only with obviously huuge input lag.
Somehow This reminds me of other method, tad bit complex, than this is but is much much more accurate by using a : gps results of the distance, stopwatch and elementary school math, yeah..
i have a vague memory of using the formula to count total time it took from point a to point b with given speed and distance...

So if creation of rocket and space travel are being precisely calculated with math, i have no doubts
(This is by far the only useful form of math and skill applicable in real life)

[Thejohnnyoshow]

so are we saying a car rated for 32mpg really getting about 5-7% less (about 30mpg), seems kind of scammy to me maytbe that the other reason they do this

[paulkibler]

If that's the case and I can say, I have 1/50 less miles on my car, then what it actually says. So, if my car has miles on it, I can actually say it has 98000 miles on it.

[ryanbell]

I had my speedo at 78 on an A road and went passed a camera. GPS speed will be about 74, so im hoping i wont be getting a ticket

[johnmurrell]

The results are invalid unless you have set the tyre pressures to the correct values using a calibrated pressure gauge. The 'results' do not confirm if the GPS, Car or both are wrong - there are several reasons the GPS can give a wrong result. The best way to check the speed is to drive on a motorway at a fixed speed and then get someone to count and time the markers by the side of the hard shoulder - these are supposed to be quite accurate. By the way you may be prosecuted for driving without due care and attention from the contents of this video..