same problem here... (also the km readings are higher by around 20%, ie. clocks 1.2kms every 1km i travel... will be - factor when i sell the car)
in my case, the problem most definately is the small tyres that came with the car as my mechanical-minded friend told me (read sky80y) the tyres on the car atm are 195/55/15s... i'm getting 205/60/15s soon...