It used to be that only the CIA, James Bond and Spider-Man had the technology necessary to attach a tracking device to a vehicle and keep tabs on it wherever it goes. But now that GPS trackers are cheaper than TV sets, everyone from local police to car-rental companies are getting into the act. And with the Barack Obama administration urging the Supreme Court to allow warrantless GPS tracking, the number of vehicles trundling around with tracking devices attached might be getting a lot higher soon. Is your car one of them? We'll show you how to find out.

Battle Brews Over FBI's Warrantless GPS Tracking FBI Vehicle-Tracking Device: The Teardown Video: The Dissection of an FBI Bumper-BeeperPassive Trackers —————-

The easiest trackers to, er, track down are older, cheaper passive trackers. These collect data but don't beam it back out, instead storing it on an internal drive that has to be retrieved. They also run on their own battery pack, and usually have relatively weak antennas. Add up these factors and you're most likely to find one in an easy-to-access place, like the undercarriage of your car, the wheel well, or inside one of the bumpers. They can't see through metal, so don't bother checking your truck or under the hood for these.

How to find it? Just get under your car and look around. If you see a black box, give it a yank. If it comes free, it's probably not factory-installed. Even if you're not sure what a normal car underside looks like, a surveillance device is going to look out of place. While you're at it, check the car cushions and unzip your headrests; those are

both fine places to hide a passive device.

Active Trackers —————

More-recent devices not only gather your GPS location data, they send it back out to someone who may be following your movements on the internet right now. Many of them can be spliced right into your car's electrical system. No batteries and no need for retrieval mean that your shadow can be extra-sneaky when hiding the device. The engine compartment is going to be too hot, and the trunk is basically a metal box, so you can still pretty much rule those out. Start by looking behind the console, and don't stop until you've looked pretty much everywhere else.

Alternately, you can pick up a GPS detector, a handy device that can detect active devices. Be careful, though: Many active devices only send out info intermittently, and only when the vehicle is moving. You're going to have to find a friend – if you have any you can trust – to wave the device around while you drive, looking for evidence of privacy-invading data transmission. And avoid crowded areas: Someone talking on a cellphone on a nearby sidewalk can give you a false positive.

Deep Cover ———-

Todd Morris, CEO of BrickHouse Security, says he sells a high-end device that can track your location even if it's "in a safe, in a van, in an underground parking garage." These devices rely more on cell-tower triangulation than GPS signals, but they can still tell the Powers that Peep where you are with startling accuracy.

Can a GPS detector find those sorts of devices? If you're such a high-priority target that someone's placed a state-of-the-art tracker on your vehicle, can you afford to take the chance? There's almost no chance a cursory investigation is going to find one of these gadgets. Your only choice is to have the car stripped down completely by a mechanic – preferably one you've got something on – and reassembled. Then of course you'll have to do it again and again, because if they're not watching you now, they might be a week from now.

Or, as a last resort, you can switch to a bicycle to transport you to and from your private deeds. Not much space on one of those to hide a tracker, plus your heart will thank you, even if your enemies don't.