This is the first step in my prophetic idea....
5 years ago I theorized as safety standards get more stringent there will be in place a system to overide the vehicles speed to set it to that of the current road via GPS. Sensors either on ground or from satelites will tell your ECU what the speed limit is for the road you are traveling and restrict travel faster that that limit.
All this is theory, and it would drastically negate a whole lot of gov income due to speeding tickets, but it is still valid as a posibility.
One step closer to automated cars driving point A to B without human involvment. Its comming.