According to those roadside radar wagons, mine reads exactly +10 from 42mph (reads 52) all the way to 105 (reads 115). Not sure about the odometer but, on a 100+ mile run, it's within 3 miles of the digital one on the OL's Lowrider and maybe 2 miles of the Mapquest guestimates.

Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python