So i was in sports authority buying a garmin legend, and I was talking to the outdoors department guide about GPS. He was telling me a friend of his bought one and disconnected the speedometer cable from his car. The GPS unit is supposed to be accurate to a few feet (dependent on the number of visible satellites), so his speedometer should be pretty accurate.
HAs anyone else heard of people doing this? Its not the legalist thing to do, but it does keep the mileage off your car. I am suprised this is the first time i have ever heard of anyone doing it.