That might be it. I spoke to other auto mechanic's and they said it was normal for the speedometer to be off a bit. It also depends on your tire size? Improper size tires/wheels can throw off your speedometer as well as the odometer.

I have driven other cars and the speedometers are usually off a bit. My A4 is off by 5kmh (which is fine). I had an old BMW (92) and its speedo was off by 12km, while my wife's 2003 Mercedes A160 is off by 4km's. The odometer reading's are correct though.

 

Every motorcycle and automobile speedometer is off by a certain %. This is on purpose.

 

The speedo accuracy thing has to to with European speed laws. You car's speedo can not be reading slower than you are going, but it can be reading faster than you are going. In the US, the law states the speedo can be above or below by a certain percentage. My 2000 Jetta GLX was 3.5 mph off, and my 2006 A4 is off too. I timed it with the road mile markers, and used my dad's GPS, and came up with the same result. Even the trip computer showed the error. If I reset the computer while cruising, it would immediately show an average speed 3 mile an hour slower than the speedo. If I understand correctly, the European laws force the manufacture to skew the speedo so that if someone were to put oversized tires on their car, the speedo would not be reading slower than the actual speed. The European makers don't bother trying to recalibrate the speedo for US laws.

 

If they vehicle is still under warranty can the dealership calibrate it to actual speed?

 

Here is an interesting exercise to all that have speedometers showing speed different than the GPS systems they use.

Try resetting avg. speed calculator while driving at a set speed (use cruise control) and seeing what a digital output is. In my case speedometer is showing 120 km/hr, a GPS shows 116/7 km/hr and the digital trip calculator shows an avg. speed of 112/3 km/hr after reseting it and keeping the cruise control on.

Really messed up

 

My F350 indicated 70mph and the GPS 68. Meassured mile was correct. When I had a jetta the speeds would match but the milage was off -.1 mi for every 10. I have not checked the A4 against the GPS yet but in a measured 10 it is off -.2.. In my wife's CRV indicated is 70 and GPS is 68

 

For what its worth, I had a 2003 passat that read 70mph at 67mph, as does my A4. I know Mercedes and Porsche (!) are the same way, too. que estrano!

 

I noticed this right away too with the GPS. Recently however, I was driving down a road that had one of those digital readouts on the side of the road that tells you how fast you are going (I think it was for a school zone). I had my speedometer set on cruise at about 40mph or 41mph and the roadside speedometer said 37mph. I was the only person on the road too, so I know it was my speed on the display.

 

i haven't read any posts except this one, so it may have been answered.

this is true for ALL CARS........

GPS reads a more accurate speeds than the car you are riding in...

 

I set my cruise control based on the GPS speed and have driven by many officers of the law running radar with nary a pullover.

Am I lucky? Is my speedometer off? Is my GPS more accurate?

I dunno, My speedo always reads higher than the GPS and the roadside "Your speed is..." signs.

YMMV