News flash: you aren't interesting enough to be spied on. I know you like getting up in arms about your privacy and how technology makes it too easy for people to track you using technologies like RFID and GPS, but the fact of the matter is that no one cares enough to follow you while you go to rent a movie and pick up some ice cream. I'm sorry, but it's the truth.
If you're still paranoid despite your boring nature, you could always pick up this GPS jammer. Fitting in the cigarette lighter in your car, the jammer supposedly blocks any GPS signals from leaving or entering your car, just in case someone has tagged it with some sort of tracking device. It'll also knock out your navigation system, but hey, it's a small price to pay for the peace of mind you'll get, despite the fact that you're clearly mentally unbalanced.