LOS ANGELES (AP) _ There can be a price for the California dream, as local residents have learned: Brush fires, floods, earthquakes, smog and now - gunslinging motorists.

A string of shooting and rock-throwing incidents on Southern California's highways have shattered the sleek, life-in-the-fast-lane image of a culture that worships the automobile and is epitomized by the freeway.

''I get goose bumps now every time someone tailgates me,'' said pizza deliveryman Richard Balain.

''They used to give you the finger, now they shoot you,'' said commuter Susan Lundall.

One motorist seen Friday on the Harbor Freeway taped a large, hand-made sign to his car trunk reading, ''Don't Shoot 3/8''

All this in a city where people hop into their cars for a half-block drive to the market and think nothing of traveling 60 miles to dinner or a show.

Dozens of vehicles, including two police cars and a tour bus, have been the target of random gunfire or rock throwing on area roadways since mid-June. Four people have died and two have been wounded.

Los Angeles Police Chief Daryl Gates, who has urged his motorcycle officers to don bullet-proof vests, called the rolling hostility a ''Road Warrior'' mentality. Predictably, police are edgy.

Last week, the California Highway Patrol briefly closed two freeways after a security guard spotted what he thought was a gunman armed with an Uzi submachine gun. It turned out to be an 8-year-old boy with a squirt gun.

But Southern Californians cope with brushfires, earthquakes and other hazards of paradise, and they seem to be coping with highway violence, too.

Some motorists are installing bullet-proof glass and shatter-resistant film on their cars. Others are rethinking the routes they take or the way they drive on roadways that, in many cases, are a second home.

''I used to always take people on freeways, now I always ask a passenger if he or she would mind if I take the side streets,'' said taxi driver Seleshi Telahun.

''I haven't honked at anyone in at least a week. And if someone wants to pass me, I let them,'' said plumber Bob Williams, adding that he also makes a point to look straight ahead.

''I'm having to rethink routes,'' said Joe Molina of Woodland Hills, who has garaged his Bentley and now drives his Lincoln because ''it's a lower profile.''

Limousine driver Giaus Ibe said he no longer weaves in and out of traffic, explaining, ''I wouldn't want anyone to think I was trying to cut them off.''

O'Gara, Hess & Eisenhardt Armoring Co. of Cincinnati, which fortifies the presidential fleet of vehicles, has had more than 20 inquiries from Southern Californians who want highway protection, said president Nick Carpinello.

''They are interested in our smash-proof, intrusion-proof vehicle,'' he said. ''We have a special glass that gives ballistic protection, and basically, that's what they are looking for.''

Some experts blame the highway violence on increased congestion. As the city's swelling populace moves farther into the suburbs, the drive to and from work takes longer and the highways get crowded. At any given moment, an estimated 2.5 million vehicles are traveling on area freeways.

''The congestion has never been worse than it is today, and the potential for conflict is even greater,'' said CHP Chief Edward Gomez, commander of California's Southern Division.

Psychologists say motorists develop chips on their shoulders about 45 minutes after they get into their cars.

''It's during those rush-hour times that you'll find the highest rate of overeacting to minimal provocation, and the amount of restraint you practice will get lower and lower,'' said Scott Fraser, an assistant professor of psychology at the University of Southern California.

Some observers suggest the news media is to blame for the rash of violence. Ray Novaco, a social ecology professor at the University of California, Irvine, said it ''provides marginal personalities a script to enact.''

But Ernie Garcia of the California Highway Patrol disagrees.

''We feel the people have a right to know this is going on and it is the duty of the news media to inform them,'' he said. ''These are cases of gunfire and they have happened before, but not as frequently as they are now.''