LoJack is one of the most famous examples of car security that uses radio tracking to hunt down and recover stolen vehicles. Most tracking devices share the same principal: Small transceivers are hidden somewhere inside the car and can be tracked by an outside source tuned to the proper frequency. Because GPS receivers require line-of-sight to an orbiting satellite to acquire a positioning fix, systems like the LoJack have the advantage of tracking cars in some places GPS will fail.

Due to close ties with law enforcement organizations, LoJack homing devices actually show up in police computer systems. LoJack units are tied to a car's unique vehicle identification number (VIN), so when a car is reported stolen and the VIN is entered into the state police crime computer, that automatically triggers the LoJack Unit in the vehicle [source: LoJack].

And LoJack stands by its product with a 24-hour recovery guarantee. Basically, if your car is stolen and can't be found within 24 hours, you get your money back -- for the LoJack, anyway [source: LoJack]. The downside to LoJack's police partnership is that the recovery system is only good in certain counties in the United States -- and it's expensive. The basic version of LoJack costs $695, but owning one could potentially save you up to 35 percent on automobile insurance [source: LoJack].

Now that we've touched on OnStar and LoJack, two of the biggest names in car security, let's take a look at how BMW competes against GM's OnStar juggernaut.