I don't rememeber what post I had where I detailed the "Pay Per Mile" program, that will turn all roads into toll roads, but this is the module they will use.

Or one like it.

It plugs into any 1996 or newer car. It uses the cell network, not sure if it also uses GPS, I would imagine so.

It will work with the sensors already in the roadways to know where you are, when you drive, and bill you, eventually.