Actually, I remember a while back there was an issue where a car rental
place back east used the GPS technology in their cars (normally used for
navigation) to fine the driver when the system indicated that the driver was
driving excessively fast.  They 'hid' the rules and specifications in the
rental agreement and if you questioned your bill when you turned in the car,
they would show you the rental agreement and then show you on a map the
exact location where you were speeding and the exact speed at which you were
traveling.