Automakers are finding that safety sells.

For years, U.S. automakers have resisted following their European cousins by shying away from advertising safety devices in their cars. That's changing.U.S. government regulations have caused a big part of the switch by requiring passive restraint systems, such as air bags or automatic seat belts, on the driver sides of all U.S.-built cars beginning with the 1990 model year.

Chrysler Corp. has taken the lead among U.S. companies in promoting safety features, especially air bags, which it supplies as standard equipment in all of its North American-made cars.

"Initially, it was tough getting customers to talk about safety," Chrysler Corp. spokesman Tony Cervone says. "It becomes a discriminating factor in buying a car now."

Chrysler is devoted part of its "Advantage: Chrysler" advertising campaign to testimonials by survivors of crashes saying they owed their lives to air bags.

General Motors Corp. recently announced it will equip all U.S.-built passenger cars with driver's-side air bags by the fall of 1995, but the company has yet to work them into safety-related advertising.

Company spokesman Donald Postma says the upscale Cadillac division is expected to be the first to promote air bags.

Ford Motor Co. has air bags in about half its 1990-model U.S.-built vehicles, but the company doesn't go to lengths to promote them or motorized passive restraint seat belts.

Under federal law, all cars made in the United States after Sept. 1, 1989, must have either an air bag or automatic seat belt for drivers and front-seat passengers.

According to Insurance Institute for Highway Safety in Arlington, Va., air bags were equipped in 1 percent of the estimated 10 million 1987 model domestic and import cars sold in the United States. By 1996, 90 percent of cars are expected to have air bags, the institute says.

European carmakers Mercedes-Benz, BMW and Volkswagen long have incorporated safety promotion into advertising, in part because buyers ask more questions.

"When you deal with a small market niche such as ours is in the United States, you have to be very attentive to what customers say they want in a car," says John Chuhran, a spokesman for Mercedes-Benz of North America in Montvale, N.J.

In one 30-second television commercial, Mercedes, which sells about 75,000 cars a year in the United States, promotes its standard safety features.

"Of course you want a safe car for your family. But what is safe? Well, only your authorized Mercedes-Benz dealer offers . . . system with driver's-side air bag and anti-lock brakes on every new model. Standard. That's safe," the announcer says.

An air bag, usually concealed in the steering wheel, inflates within a tenth of a second upon a head-on impact or one 30 degrees to the left or right of center of the car. Air bags are designed to be used in addition to lap and shoulder seat belts.

Automakers acknowledge that air bags add no safety margin to side or rear impact accidents.

"In terms of advertising," says Mercedes-Benz's Chuhran, "safety is a relative term. There is no such thing as an absolutely safe automobile."