The easiest way to check the speeedometer reaing is if you have mile markers along your highway and use a stop watch. If you don't have mile markers, then take a stop watch and drive at what your speedometer reads as 60 MPH. You should go 1 mile in 1 minute at that speed. If you go less than a mile then your speedometer is fast. The other easy way is if you have a friendly patrolman around with a radar unit that will let you drive you car at various speeds and he can record on the radar what you were actually doing. The rest some of the Backdraft people will have to answer.
Ron
