In Reply to: Sorry, you are just incorrect about the error rate posted by vidterry on February 27, 2001 at 01:04:26:
BMW's PUBLISHED figures on speedometer error acceptable limits states that the error can be as much as 10% PLUS 1.5mph and still be considered in tolerance.
Your figure of 2.5mph is to far off to be helpful.
At an indicated 142, the speedo error could in fact be misstating the speed by 15.7mph...meaning that the car MIGHT have only been going 126.3 mph, certainly not enought to trigger the limiter.
Neither BMW nor I are saying that all speedos are off by that much, just that they CAN be and still be in BMW tolerance. Much has been said about this being far too wide a tolerance, and I completely agree. Fact remains it IS BMW's published spec, and some on this board have reported speedo errors IN THAT RANGE.
If you have tested YOUR car, and found it's error rate to be as LOW as you suggest, great...but I think it is wrong to state as fact that the error rate for all Z3s and ///M Roadsters is 2.5mph. Just isn't the case.