Velouria
Long time lurker
The unofficial leeway is +/- 10%, but the bastards can still do you for 1mph over. The law is the lawAlf Klein said:Just read the link. What is this piston heads site? Looks like some dodgy car fiends site to me so I don't trust it. That whole, just trying to raise money bit seems spurious to me. If you don't speed, you won't get done for speeding. If you do, then you deserve it.
On your point about catching people doing 32 mph, if there were more or less blanket coverage of speed cameras, then it would be easy to identify people who just strayed over the speed limit by a small ammount and then they could appeal. Or something like that. Also, can you be done for doing 32? What is the accuracy requirement for car speedometers?

Traffic police cars (and bikes) have accurate speedos that should be calibrated very regularly. Once a week, or daily - can't remember which.

