Perhaps you have either not looked at the proposition (links in my second post on this thread), or you do not believe that it is possible to have a benign GPS device in a car.

Lets see if I can explain it in a way that you might understand. Early satellites were low powered and receiving dishes on the ground needed to be quite big, not quite the Aracibo Dish but still big, you still see these old dishes occasionally. With more powerful satellites and improved technology for the receivers, the receiving dishes could be smaller. With GPS devices the receiver is built into the device. In order for the GPS device to communicate back to the satellite it would need a dish that would not be good for the aerodynamics of the car and also a way for the dish to actively stay pointed exactly at the satellite. And oh wait, the GPS satellites were never built to handle the real-time reporting of positions of 200 odd million motor vehicles.

Of course you might argue that the in-car GPS device could send information back to the man using the cell phone networks, that's all well and good, if all the vendors hand over a substantial amount of bandwidth and all roads have cellular coverage.

So your fears actually have no basis in reality, unless of course you bought a cell phone with a built in GPS.

The benefit of a GPS based system over an odometer based system, is that the GPS can differentiate between in-state and out-of-state mileage, on road and off road, private road and public highway, and also time of day. Different roads at different times of day can be charged at different rates. Charges associated with use of toll roads and toll bridges, could be paid at the next visit to a gas station. Information about congestion due to accidents, road works, rush hour, flooding, mud slides, etc. could be fed to motorists to prevent unnecessary delays.

It is not the infringement of your liberties that you perceive it to be.