I noticed the other day that the Digital speed indicator was 10mph higher than the Analog dial. I know the car is not a plane and the difference is not the air speed vs ground speed. I pulled into a Gas station filled up with gas and was on my way. After I left the gas station everything was fine. So, I thought the problem had something to do with the amount of gas in the tank...

Well, the issue happened again a day later. Once I stop/start the car the problems goes away.

Any suggestions?

 

Get it fixed if its under warrantee.

 

if you changed your wheels/rims, this will have an effect on the speed reading

also, the 986/996 generation digital speedometers (or many of them) have been known to be +3mph static across all speeds.

 

My turbo reads 80 when I am doing 75 (GPS verified). I have no idea whether the digital and analog guages are the same because I never look at that analog unit -- it is worthless.

 

No changing of tires or wheels. 90% + of the time digital & analog are identical. However, I noticed two times the 10mph difference, and after restarting car the difference went back to zero.... I don't know how to reproduce this issue, so I guess it will be difficult for the dealer to reproduce.

 

I was told that Porsche allows a 8 mph range variance.