Bobby Hillin Jr., 22, yesterday became NASCAR's youngest winner by beating Tim Richmond by half a length in the Talladega 500 at Alabama International Motor Speedway before a crowd of 105,000 in Talladega, Ala.

He passed Richmond on the 180th lap of the 188-lap race.

Bobby Allison, Hillin's teammate, started a six-car wreck going into the last lap by trying to catch up. With Hillin driving his Buick LeSabre faultlessly to the finish line on the 2.66-mile, high-banked tri-oval, Allison skidded up the banking and hit Rick Wilson's car. Cars driven by Joe Ruttman, Kyle Petty, Davey Allison and Jim Sauter piled up, too.

The race was one of the most competitive in NASCAR history, with 48 lead changes and a record 26 drivers leading at one time or another.

Hillin earned $60,055 by averaging 151.552 mph . . .

In Hockenheim, West Germany, Keke Rosberg and Alain Prost were running one-two with two laps to go when their engines began to sputter. After they ran out of fuel, Prost tried pushing his car but gave up 100 yards short of the finish.

Meanwhile Nelson Piquet's Williams-Honda zipped past and won the German Grand Prix. Prost was placed sixth just behind Rosberg.