Hello,
I've noticed that the speed meter shows 8-9Km/h faster than the real speed. I've tried several times with friend of mine setting the autopilot at for ex. 80km/h and I've seen them slowly leaving me behind. I don't know if there is any possible calibration a=i can do myself without paying lots of money fixing it with programs or sth like that. It's not that disturbing after all.
thank you.

My Croma (when I had it) read about 8% high as measured against GPS speed which is accurate to 0.1MPH. Our Barchetta is similarly reading on the high side.

I seem to recall the EU homologation rules dictate that the vehicles speedometer must be within 10% of true speed at all speeds. I also recall that most manufacturers used to implement and comply with this requirement by indicating 5% to 10% high and thus keep the motorist on the safe side of national speed limits.

HOWEVER..... my new 500X is reading true speed +/- 1 MPH. Thus far I've tested this to 80MPH so it could be that more modern cars with improved speed sensors are choosing to be very accurate and within +/- 1% (or so).

The last thing you want is a car that reads up to 10% low as you will certainly end up with speeding tickets!

My Croma does this too but I think it hovers around 8-10% no matter what the speed.... so 40 is 44 80 is 88 120 is about 130 etc....

What sized wheels and tyres do you have fitted?

If they've been changed from stock that could have an impact.