U.K.-based Cobra produces quite a range of car accessories, from headrest-mounted DVD players to parking aids. Looking for GPS tracking systems? Cobra's got them. But Cobra also sells a car security device known to stop thieves in their tracks. The Cobra 8510 immobilizer's name alone should give you a pretty good idea about how this car security system works. It's accredited by the Thatcham organization, which tests and rates vehicle security systems. Immobilizers work by disabling components of the engine that are necessary for startup. By shutting down the ignition system, immobilizers make it extremely difficult to hotwire a car and start it up without a key [source: CarsBuddy]. The Cobra 8510 comes with two keys that can deactivate the system -- as long as you keep them safe, your car shouldn't be going anywhere without you in it.
The Cobra arms itself automatically -- without a key, car thieves will have serious trouble making off with any car they break into that's fitted with an immobilizer. And compared to GPS solutions or other multi-feature car security solutions, immobilizers come at a low price. The Cobra 8510 costs about $65 on Amazon.co.uk.