If you're the type who just may be the victim of undercover GPS tracking (read: promiscuous), you should give some serious thought to this one. This simple cigarette adapter plug-in reportedly "knocks out GPS logging or GPS tracking systems that may be operating in your vehicle," and considering that it sports a two-to-four meter operating range, just about every automobile outside of an 18-wheeler (or limousine) should be covered. Unfortunately, there's no word yet on how much this potential life-saver will cost, but its slated to ship "soon" to the devious and uber-paranoid sects.
There'd be a few ways of tracking a car -- or, perhaps, its driver -- and GPS is only one. A stalking former husband who murdered one of my wife';s clients a couple of years ago just relied on a network of friends and relations to find the woman.
Once again, if you have any suspicions that your car has been tampered with, you do need to get someone independent to find it or to help you find it, so that there is a witness, and no one can say that you bugged your own car to persecute your former boyfriend.
You really need some legal advice about the entire situation, because what you really need is an end to the stalking, rather than a crash course on modern surveillance techniques.
I know what it's like being a student, so I am not going to advise you to pay out big for a solicitor, but here in Australia there are several provisions for you to find out your entire legal position without being sent bankrupt in the process.
One is what we call a "Chamber Magistrate", who is a court official who can advise you of legal issues in relation to the court's powers, and will help you lodge any processes or even sometimes write you a letter to help solve a problem.
Another is the community legal centre, where a small group of solicitors work together on an income partly paid by the Government. They will help people with legal questions, and refer them to an appropriate legal firm if the problem seems to require a lot of detailed legal work.
A third is a very useful publication known as The Law Handbook, published by one of the larger legal centres, and providing a good overview of NSW law.
I would be surprised if there are not similar provisions in the US, if you look for them.
Your aim would probably be to take out something along the lines of what we know as an Apprehended Violence Order, which would prevent your ex from approaching you, speaking to you, tracing your movements, causing others to do any of these things to you on his behalf, and so on.
I hope you are soon in a position to feel safe again.
Because of its small size, discrete color, and rear facing magnet, the device can be stowed away in any number of locations ranging from the underside of a vehicle, within the front / rear bumper, rear trunk, front glove box, or underneath a driver / passenger seat. The included LandAirSea Tracing Key documentation explains the effectiveness of the device based on placement outside or within the vehicle.
Both the battery compartment - secured with four screws - and USB port receive protection from water & dirt with silicone seals. Two small LEDs inform the user of sufficient battery power & satellite activity.
Good Luck :D