I don't think you are correct - my speedo and sat nav usually show the same. I think you are confusing the fact that a 3% is anecdotally allowed as a margin of error by the police rather than all speedos set at 3% too fast.
WPA2 hack: How secure is your Wi-Fi?
HP’s new Surface Pro rival is designed specifically for Adobe-using designers and artists
Best kids apps for iPhone & iPad
Que faire si son iPhone ou iPad est tombé dans de l'eau ?