Ayrton Senna of Brazil took over the lead on the 39th lap and cruised to a 31-second victory in the fifth annual Detroit Grand Prix Sunday in Detroit.
Senna, driving a Lotus, covered the 63-lap race on the 2.5-mile street course in 1 hour 51 minutes 12.847 seconds.
Jacques Laffitte of France finished second, and defending world champion Alain Prost of France was third.
The victory was Senna's second of the 1986 Formula One season and fourth of his two-year career. He won the Spanish Grand Prix in April.
Senna's victory moved him into first place in the world Formula One driver's standings with 36 points. Prost fell to second with 33 points. Britain's Nigel Mansell is third with 29.
Senna grabbed the lead from Nelson Piquet on lap 39 and built a margin of more than eight seconds over the next three laps.
While attempting to close the gap between him and Senna on lap 42, Piquet crashed into the outside retaining wall on Turn 19, heading to the straightaway. He was not injured, but was forced to leave the race.
On the previous lap, Piquet turned in a record speed of 88.904 m.p.h. Senna set the old mark in last year's race at 85.218 m.p.h.
Michele Alboreto of Italy, the 1983 Detroit winner, drove his Ferrari to fourth place, the last car on the lead lap.
Mansell, who failed in his attempt to become the first driver to win three consecutive Formula One races since Alan Jones of Australia in 1979, was a lap down in fifth in his Williams-Honda. Riccardo Patrese of Italy took the last championship point Sunday, finishing sixth in a Brabham-BMW.
Senna, who said he was heartbroken over Brazil's loss to France in the World Cup soccer tournament Saturday, gained a measure of revenge by turning back the French drivers.
After he finished, Senna stopped long enough to take a small Brazilian flag from a fan before making a triumphant victory lap around the downtown Detroit street circuit.
"I did not beat any French or anybody," Senna said. "I raced for my country and I'm glad we won."
Polesitters Sarel van der Merwe and Doc Bundy won the inaugural Grand Prix of Palm Beach when Bundy took the lead on the 103rd lap and hung on to defeat Darin Brassfield and Jochen Mass by .393 of a second at West Palm Beach, Fla.
It was the second victory in seven starts in the 1986 International Motor Sports Assn. (IMSA) season for Rick Hendrick's Corvette GTP. Brassfield and Mass drove a BF Goodrich Porsche 962 and would have won a $40,000 bonus for first-time IMSA winners if they had finished first.
The winners averaged 72.172 m.p.h over the 1.6-mile, 10-turn course through part of downtown West Palm Beach and split the first prize of $25,000. There were 136 laps run for a total of 217.6 miles.
Brian Redman and Hurley Haywood finished third in a Jaguar XJR-7; Al Holbert and Derek Bell were fourth in a Porsche 962, and Jim Busby and John Morton were fifth in a Porsche 962.
"I think people have changed their minds about the Corvette from the beginning of the season," Van der Merwe said of the Hendrick Motorsports car. "People are taking us seriously now."