In Holland they are planning to replace the current roadtax system (based on the weight of the car and the type of fuel used) by a GPS based system that will track your car at a dense grid of specific measuring points to see to what extent you have been driving during rush hours or during the less busy parts of the day. If you avoid the rush hours you will be taxed accordingly lower.
Of course the GPS system requires a sensor in your car, so the electronics industry is all for it. And yes, it can be used for other purposes as well.
Introduction has seen many delays, as it is actually a type of political suicide.
"I find the whole business of religion profoundly interesting, but it does mystify me that otherwise intelligent people take it seriously." Douglas Adams