For car-owners -- stealing the opportunity from car thieves

Stealing most cars is too easy -- and too often the motorist cooperates with the thief. Roughly two cars are taken every minute of every day of the week. Beyond that, more than twice as many have accessories or contents ripped off. Car theft, in fact, has gone up tenfold in the last 10 years.

The National Automobile Theft Bureau in Palos Hills, Ill., estimates that the economic loss from car theft is $4 billion a year, including the cost of trying to recover the stolen vehicles themselves.

And how does the motorist cooperate? A study by the National Institute of Justice for the United States Justice Department reports that in 4 out of 5 cases of theft, owners left the doors unlocked and in 1 out of 5 cases the keys were left in the ignition.

For the alert motorist, antitheft devices offer another level of protection for the car.

Deterrent devices are designed to create delays and make a thief think twice about stealing a car. Some of them interrupt the electrical or fuel system; some sound an alarm, such as a horn; others flash the headlights or transmit a signal to a remote paging unit; and others lock the hood, brakes, or steering.

Antitheft products detect a problem in a few basic ways. Audio sensors ``listen'' for a broken window, but try to discriminate it from the noise of normal entry. Current sensors can detect the opening of a door or trunk. Motion detectors try to separate jack movement from normal wind buffeting. The best deterrent is a combination system that eliminates the disadvantage of each individual device.

An auxiliary battery is an add-on that will operate the antitheft unit even if a thief cuts the wire to a car's battery. The duplication adds to the expense, but it increases the system's reliability.

Another class of deterrents is much less expensive. Included in this group is the relatively simple steering-wheel and brake-pedal lock as well as hood locks to keep a thief out of the engine. The simplest and cheapest, however, is the ``toothless tiger,'' a window decal announcing the presence of an alarm system that doesn't exist.

The awful inconvenience caused by a stolen car is a great motivator to buy a theft-prevention system. Also, most insurance companies will discount the premiums, which should almost pay for the system in a few years.

Security systems can be purchased as an optional feature on a new car or installed later. Professional thieves usually know the systems supplied by the dealers or manufacturers and find these cars easier to steal than ones with devices installed in the aftermarket.

Many companies sell car security systems. Write for information and study the systems with your particular needs in mind. Then talk to a local car dealer. Installation of some of the high-tech systems can be as expensive as the sophisticated systems themselves and just as important. A reputable installer will guarantee his work.

Many experts believe that the first thing to do before buying a security system is to put your vehicle identification number (VIN) on high-theft parts, such as the doors, bumpers, fenders, grill, and hood. At present the manufacturer stamps only the engine and transmission with the vehicle ID number. In 1987, however, 14 parts will be marked this way. It will be a federal offense to sell or possess a car part with a defaced VIN.

An engraving pencil can be used to mark your car's parts and can probably be borrowed from the local police station. If a thief knows the parts have been marked, he is more likely to pass up your car in favor of one with untagged parts. A kit is also available to etch the windows with the VIN, making it a less-likely candidate for chop shop or resale.

Even if you don't buy an antitheft device, there are precautionary measures to keep your car from being an easy mark. Here are a few of the most effective:

Always close all the windows and lock the car.

Make your car difficult for a thief to tow away. Park with the front wheels turned sharply right or left. Always use the emergency brake. If your car has an automatic transmission, put it into park. If you have a stick shift, leave it in gear.

Never leave packages, valuables, a CB radio, or tape deck in view.

If possible, park in a well-lit area at night.

If you turn your car over to a parking attendant, leave only the ignition key. Make sure that the key number does not appear on the key you leave.

Never leave your license, car registration (unless more than one person drives the car and it is inconvenient to keep it in your wallet), titles, or materials with residence information in the vehicle.

If you've bought an antitheft device and are practicing good preventive techniques, the only things left are to move from a ``high risk'' city and sell your Corvette.