Theft-deterrent systems fall into two general categories: active and passive.
Active devices, as the name implies, require owners to take some action, such as setting the alarm, installing a locking device, and so on.
Passive systems require no action; they engage automatically once the keys are removed or the doors are locked. Engine immobilizers are a popular passive device.
Experts like Kim Hazelbaker, senior vice president of the Highway Loss Data Institute, and Ed Sparkman, an agent for the National Insurance Crime Bureau, agree that theft-deterrent devices don't guarantee your car's security, but they do decrease the chances for theft. Thieves spotting such devices probably will move on to easier-to-steal vehicles that aren't protected.
To that end, the NICB recommends what it calls ''layered protection." The rationale is that the more layers of protection on your vehicle, the more difficult it is to steal.
Other second-layer favorites include:
Tools such as starter disablers, fuse cutoffs, and kill switches prevent thieves from bypassing the ignition and hot-wiring the vehicle.
Other systems feature smart keys, which carry computer chips or coded radio frequencies. The engine can't be started without the exact key.
Vehicles with engine immobilizers generally are stolen by hauling them away on flatbed trucks, a visible act that takes more time.
These devices are systems that help recover stolen vehicles. Such systems as
OnStar is available on most GM models -- and on several other brands such as Acura, Audi, Isuzu, and
LoJack installs a transmitter the size of a chalkboard eraser in one of 20 potential spots on a car. The location is kept secret so thieves can't easily disarm it. The transmitter starts working only when police, who receive a stolen-car report, activate it by remote control.
This system also costs about $695 and is installed on new vehicles by a dealer or can be purchased directly from Massachusetts-based LoJack.
LoJack is available currently in 22 states and the District of Columbia, but the Insurance Information Institute reports that it offers more than a 90 percent recovery rate on stolen vehicles.
If you choose to install OnStar, LoJack, or another tracking system, be sure to apply warning decals to your vehicle. By making them aware of these tracking devices, thieves may think twice before stealing your car.
What you drive should help determine the kind of protection you need. Heavier layers of protection should be considered if you drive a car that's a favorite among thieves, such as the Cadillac Escalade EXT or Nissan Maxima.
More than 1.2 million motor vehicles were reported stolen in 2004 in the United States.* The top 10 targets of thieves were:
1.'95 Honda Civic
3.'91 Honda Accord
4.'94 Dodge Caravan
5.'94 Chevrolet 1500
6.'97 Ford F-150
7.'03 Dodge Ram
9.'88 Toyota Pickup
10.'91 Nissan Sentra
SOURCE: National Insurance Crime Bureau (2004 data) via Cars.com