Speedometer error

Question... I just bought a 2013 SW and I have noticed that when comparing my GPS to the analog and digital speeds on my Jetta they do not match. The vehicle (both analog and digital) will read 62mph but the GPS reads 60mph. Now before anyone tells my that I can not trust the GPS I have tested the GPS in 10 other vehicles and the GPS matches the readings correctly. So I do not want you to reply to this message if you are going to say that the GPS is wrong... please. It is a new GPS. The reason I say this is because of old threads I saw from around 2000. Anyway, is there anything I can do about that... or the dealer... or mechanic.

This might interest you

http://forums.tdiclub.com/showthread.php?t=385766

And why would someone tell you GPS is not precise lol...

Common Question

It is a common question. Here's a current link: http://forums.tdiclub.com/showthread.php?t=365368

My 2000 is 3 MPH off. So is my 97 Ford Explorer. Both say 68 and I am going 65 according to highway Speed Boxes.

Mine was reading slightly higher than my SGII until I physically moved the needle CC on its shaft. The needle now rests below 0. I had taken the cluster apart to check why my fuel gauge dips every so often. A different stepper motor did not cure it, but I digress.

Doh!!!

I see the new post now... thanks. Call me a search virgin.

I have a 5mph problem on on 06 Jetta

The faster I go the more mine is off. I bought a scan gauge 2 and it is right with my gps so thats what I use.

Demo3 said:

Question... I just bought a 2013 SW and I have noticed that when comparing my GPS to the analog and digital speeds on my Jetta they do not match. The vehicle (both analog and digital) will read 62mph but the GPS reads 60mph. Now before anyone tells my that I can not trust the GPS I have tested the GPS in 10 other vehicles and the GPS matches the readings correctly. So I do not want you to reply to this message if you are going to say that the GPS is wrong... please. It is a new GPS. The reason I say this is because of old threads I saw from around 2000. Anyway, is there anything I can do about that... or the dealer... or mechanic.

Click to expand...

I am dealing with the same situation with a 2013 jetta tdi and my gps is dead accurate. I put my car on a dynonometer with a computer read out, paid $125 and also discovered that my odometer is clocking on 4.4% more kilometers than it should. The dyno registered 91 kms./hr while the digital display what the driver sees read 100 kms./hr. Now we are going to arbitration, I am not going to take any more bs from vw of canada and their dealers anymore. They need to fix this.

I trust my GPS ...

I always considered my Jetta to be about 1% slow with odometer and about 2 miles per hour fast with the speedometer. My GPS proved that to be correct.

Long before I got a GPS, when I purchased new tires, I'd do Mile Maker checks ....... several of them and do an average to confirm the status of the odometer for my Excel spreadsheet formulas.

Both my tdi & ML (bought new) read 4-5 mph faster than actual.

I figure that calibration for speedo had to do with tire size,
my Beetle is stock and ML is special edition (custom factory wheels) -

I would be curious to know the reason as well !! 6 to 7 % is a lot.

AndyBees said:

Long before I got a GPS, when I purchased new tires, I'd do Mile Maker checks ....... several of them and do an average to confirm the status of the odometer for my Excel spreadsheet formulas.

Click to expand...

I did the same. I might have a problem

ron planiden said:

I am dealing with the same situation with a 2013 jetta tdi and my gps is dead accurate. I put my car on a dynonometer with a computer read out, paid $125 and also discovered that my odometer is clocking on 4.4% more kilometers than it should. The dyno registered 91 kms./hr while the digital display what the driver sees read 100 kms./hr. Now we are going to arbitration, I am not going to take any more bs from vw of canada and their dealers anymore. They need to fix this.

Click to expand...

Respectfully, ~~~~ VW is up to their ears in Dieselgate. My guess is your issue is valid, but a lost cause

At 60 mph (100 kph) our Jetta reads 10% over. I brought this up at the dealership and was told this was within allowable tolerances. I figure if this same attention to detail carries through other read outs then I can't really believe anything Heidi says.

ron planiden said:

I am dealing with the same situation with a 2013 jetta tdi and my gps is dead accurate. I put my car on a dynonometer with a computer read out, paid $125 and also discovered that my odometer is clocking on 4.4% more kilometers than it should. The dyno registered 91 kms./hr while the digital display what the driver sees read 100 kms./hr. Now we are going to arbitration, I am not going to take any more bs from vw of canada and their dealers anymore. They need to fix this.

Click to expand...

I hope you didn't change tires or check this with worn tires. Your speedo will read higher as your tires get smaller because you're travelling a shorter distance than it thinks for every revolution. Even different brand tires (both of same size) can result in a small discrepancy. GPS doesn't care about tire size, revolutions, etc., so it's always going to be right.

Mine was about 2% high on the original set. Changed to 4% high on my second set of tires.

"Drive more, worry less" applies.

The speedometer (digital and analog display) reads slightly high by design to comply with a law in Germany and supposedly in the rest of Europe which says a car's speedometer can never under-report the true speed of the vehicle for the range of rim and tire combinations the vehicle is designed for. The speedometer is allowed to read dead-on or high, never low.

The vehicle speed can be read using VCDS. The instrument cluster knows the actual reported speed and that's what you can see in VCDS. The indicated speed on the instrument cluster will read slightly higher than what is reported using VCDS. The instrument cluster internally knows the correct speed and biases the speedometer reading slightly high to comply with the law. Although the speedometer reads slightly high by design, the odometer should be dead-on. This assumes stock rims and tire size.

The "error" in the speedometer can be tweaked some using VCDS to calibrate the indicated speed but then the odometer will be off. It's best to just leave it alone and be aware that the speedometer reads slightly high by design. It also gives you a little bit of "insurance" against speeding tickets.

Have fun!

I just do 20% over. 8)