In his second try, young Rick Mears won the Indianapolis 500-mile race today when A.J. Foyt killed his engine parking for gas and the Unser brothers couldn't make it home before their cars fell apart.

"It's almost like a fairy tale," said Mears, 27, a Californian whose rapid ascent in Indy-car racing was foreshadowed by a grand career as an off-road racer. "This thing has happened so quick it's unbelieveable."

The Indy-car rookie of the year on the national circuit last season, Mears put his Penske-Cosworth 6 on the pole with a qualifying speed of more than 193 miles per hour. In a faultless drive today in the world's only $1 million race, Mears averaged 158.899 mph.

He won coasting, finishing nearly a full lap ahead of Foyt, who crawled across the finish line at maybe 10 mph with an engine that broke on the last lap.

Though Foyt finished that close, the four-time Indy winner was not a serious challenger after a midrace pit stop cost him 48 seconds. "It was my mistake," Foyt said. "I killed the engine when I came in for fuel. We had trouble getting it going again."

The 30 seconds more than the preferred pit-stop time of 16 to 18 seconds were precious at the end. But, just as important, they forced Foyt to abandon his plan of driving conservatively.

"I intended to save the car most of the day and run hard at the end," he said. "But when I killed it, I had to run hard to catch up. I had a real good chance to win if that hadn'thappened. Hell, I passed Mears just before that and I must have passed him six times. I didn't have no problem running by him."

But Foyt's long, bold rush after the botched pit stop eventually wore out a valve in his $135,000 racer, reducing him to a$135 jalopy speed on the last lap. As he rolled across the finish line, out of power, Foyt clasped both hands over his helmet, shaking them at the cheering spectators as if finishing at all were a victory.

By his unequaled success here and by dint of his combative personality, only Foyt would stand before a judge and say he didn't believe in subpoenas, his brash act of two days ago - he owned the hearts of most of the estimated 350,000 customers here on a day when glorious sunshine replaced a predawn thunderstorm.

The race, however, belonged first to Al Unser, then to his older brother Bobby and, only last, to Mears.

Of the first 104 laps on the 2 1/2-mile Indianapolis Motor Speedway, Al Unser led 89. With 96 laps to go, his car belching flame through its exhaust system, Al Unser was forced to quit the chase, victim of a failed transmission seal that allowed oil to leak.

Until then, the three-time Indy winner has set speed records for this event, the last a 90-lap record of 166.162 mph.

Unser said it was a shame to go out because of such a small problem. And he also said it was a shame that people were cheating out there. He wouldn't name names, but listeners judged him to be speaking of Foyt, whose racing speeds of nearly 190 were unexpected.

"When everyone came in and turned up the boost and cheated, I'd have done the same thing on my next stop if I could have," Unser said, reciting the facts of big-time racing life. He said some people were cheating on the "boost" that gives cars three or four extra miles per hour and consequently was outlawed this week by the United States Auto Club.

Would Unser protest officially?

"Why would I do that? I've been in court all month," he replied, "and I'll be damned I want to do it again."

With his brother gone, Bobby Unser, a two-time winner here, took over. The Unsers in the last 12 years have won five Indys, placed second four times and third twice. From Lap 97 to Lap 182, Bobby Unser, a 45-year-old veteran of 17 Indianapolis 500s, kept the cherubic Mears, on the brickyard for the second time, in his rear-view mirror.

At Lap 163, Mears thought to pass Unser.

He wanted to do it on the front straightaway, a 40-foot-wide tunnel of fear at 200 mph. At the end of that straight comes Turn 1. An old driver, Mel Kenyon, once said going into that turn is like driving 120 mph down a city street and turning into a dark alley.

As Turn 1 rushed toward Mears, so did Unser. Mears had moved inside Unser, who, seeing the challenge, simply cut sharp into the dark alley. Not an impetuous young man, Mears did a smart thing. He took his foot off the gas pedal.

"That definitely got my heart started," Mears said afterward. "I was expecting Bobby to do that. If I hadn't been, it probably would have been trouble."

Only 19 laps later, Mears was rewarded for his alertness.

Unser led Mears by a heartbeat. At 180 mph, that's the length of a football field. The chase was on. Both drivers would need one more pit stop for fuel. They are teammates driving cars owned by Roger Penske, the creator of a splinter political group that now threatens to split Indy-car racing into warring camps.

"Both these guys are racers," Penske would say later. "We had no game plan as to which one ought to win."

On Lap 182, with 45 miles to go, Unser floated his racer through Turn 3 and moved through a short straight toward Turn 4, fully confident he was the winner of the world's most famous race for a third time.

"The race went exactly the way I wanted it," he said.

Almost.

Before he made it to Turn 4, Unser heard the unmistakeable sound of the end. His highest gear had broken. Suddenly, the engine was revving wildly, hitting 12,000 rpm out of gear. The wonder is that the engine didn't explode.

The trailing Mears, in his helmet and wearing earplugs to close out the sound of his own engine, still heard the death-rev of Unser's car.

Unser slowed down immediately - "If I'd had a shotgun, I'd have shot the car," he said - the race was over. Unser finished in third gear, able to go no faster than 120 mph, and Mears had only to stay off the walls to hold off Foyt's late challenge. CAPTION: Picture, Rick Mears celebrates easy Indy 500 victory after cars of AL and Bobby Unser and A.J. Foyt developed trouble. UPI