after 100 your speedo starts to go off, and as you go faster it goes way way way off. I was sitting with my buddy in his BMW m3 at 140 when he got hit by a radar (undercover camaro). the cop clocked us at 126. the speedo was giving a false reading, 14mph difference. And that's in a BMW, In germany there are no speed limits on the autobahn. so you would assume that a BMW's speedo would be a little more accurate than any other car.