They shouldn't be allowed to archive the data for more than 1 week, without a crime being committed, and the data has to be locked and inaccessible without a subpoena.
The tracking device should use GPS tracking data to turn itself on and off, so it is only on when operating on public roads.
Better yet, don't install them.
That's pretty much where things currently stand. If you have a recent model car, take a look at the owner's manual. There is most likely a statement in there that refers to the data logging capabilities of the on-board computer. I've seen text that goes on a bit further and discusses who might gain access to the computer data (law enforcement and insurance companies top the list). Of course, they must have a good reason to seek such data. For now, at least.