How to change the metered mph ?

[Bwingnutt]

My mph in my 01 540i seems off 5 to 10 mph off. Is this the computer and its adjustment? How can I change it to actual mph?

[MarcoZandrini]

At what speeds does the error occur? What are you using to determine that the speedo is wrong? Most speedos have a built in error that gets larger as the speed increases.

[DennisCooper]

Hi,

This isn't anything to do with Car Audio and associated electronics, so do put the question up on the E39 section.

I initially suspect that you have the wrong size/profile tyres on the car. As per above from Marco, what are you using to determine the cars speed? a GPS/SatNav unit or software? Instrument speed clusters I have read previously have a tolerance level of +/- 10% at speeds up to 100 mph and then after that it's quite a bit higher at +/- 15 or 20% I can't quite remember.

Cheers, Dennis!