An abandoned FBI vehicle-tracking device.  Photo: Jon Snyder/Wired.com

Kathy Thomas knew she was under surveillance. The animal rights and environmental activist had been trailed daily by cops over several months, and had even been stopped on occasion by police and FBI agents.

But when the surveillance seemed to halt suddenly in mid-2005 after she confronted one of the agents, she thought it was all over. Months went by without a peep from the FBI surveillance teams that had been tracking her in undercover vehicles and helicopters. That’s when it occurred to her to check her car.

Rumors had been...

From Wired How-To Wiki

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.

Passive Trackers

T...