Mine is spot on at 0. From there on, it seems to increase in error to about + 10 mph at an indicated 40, and seems to hold that to as fast as I'll go. Once, I passed a radar wagon that has a huge display showing your speed. It said 42 and my speedometer said 52. I wish I could use the tach to determine my speed, but it's off the other way, showing 6800 when I hit the rev limit.

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