Speedometer issues

[engage]

I started suspecting that my speedometer and trip computer differed significantly. So, the last time I was on a non-congested freeway, I set the cruise control at 80 and then reset the average speed on the trip 1 computer. I was able to go 20 miles without slowing down. After the twenty miles, The trip 1 computer indicated my average speed as 73 mph.

How can the trip and speedometer be so different???

[BLACKa4QUAT]

i noticed this on my b6 as well that when i'm holding a constant speed, and reset the average speed on the trip computer, the average speed is about 5 mph less than what i'm going on average. no idea why it does that. my gps said my speedo is pretty accurate, just the average speed in the DIS is off.