dk1

I have checked my speedometer reading against an after-market GPS. It shows that the car speedometer is reading 5% higher than the actual speed. For example, when the car shows 60 MPH, GPS shows 57. Odometer reading is accurate.

I have read some complaints about B7 speedometers reading up to 10% too high. Looks like B8 might have the same issue (intentional?). Anybody noticed the same thing? Any way the speedo can be calibrated?

Issaquah Coug

I've noticed a 3 mph difference (50 vs. 47), at a few speed notification signs. Not sure how to adjust.

Toecutter

Cool, less chance of me getting a speeding ticket!




Maybe...

afouralex

I wouldn't really trust the speed signs, they've never been exactly right for me in several different cars...same thing with the GPS...but at the same time, I feel like my speedo is off too...I actually know it's off because my tire size has changed but that's only supposed to be a 1% difference...maybe the car is just too good to be true 90 feels like 70mph

snagitseven

Mine reads about 1 to 1.5 mph slower than actual at 60. GPS mph is prob the most accurate measurement of actual mph you can have, assuming your speed has stabilized and the GPS has caught up to your actual speed.

dk1

AFAIK, GPS reads the actual speed. In my case it agrees exactly with my other car and with road speed signs. Audi, on the other hand, is consistently 5% too high. To measure the difference I used cruise control.

Dark_Mist

there is a 5-10% error one way or the other in all speedometers.

Fitting new tyres can alter your speedometers accuracy by up to 5%.

dman413

I'm pretty sure car manufacturers are allowed to error on the side where the speedometer is a bit high, but not on the low side. I could see a class action lawsuit if say a number of people started getting a speeding ticket in certain make/model because all the speedos were saying 65 when they were actually doing 70.

dk1

That would affect odometer reading as well. I am pretty sure a lot of people would be upset if their cars had odometer reading 5% too high.

trucaliber

Has anyone looked into this further? My 09 A3 and 06 A4 display +4MPH compared to an HG-100 HUD GPS. I verified the HG-100 is correct by taking it for a spin in 3 other cars(ford, pontiac and toyota). And only my 2 Audis are 'running fast'. They are both stock without any modifications at all. I baught the A4 with 30k miles on it, but according to my calcuations I bet it really has around 26k.