1971 Questor Grand Prix

The Questor Grand Prix was a non-championship race for Formula One and Formula 5000 cars held on 28 March 1971 to inaugurate a new racing facility in California, the Ontario Motor Speedway, built by the Questor conglomerate.

Because of the smaller fuel tanks of the F5000 cars, the race was run in two heats of 32 laps, and the final result decided by a points system. Jackie Stewart qualified on pole for Heat 1 and finished runner-up behind Mario Andretti. Chris Amon set fastest lap. Andretti and Stewart again finished first and second in Heat 2 and Pedro Rodriguez set fastest lap, quicker than Amon's time in Heat 1. Andretti was declared the winner; with Stewart in second place and Denny Hulme third. Mark Donohue was the best-placed F5000 finisher in Heat 1, and Ron Grable best in Heat 2. Grable was also the best-placed F5000 driver on aggregate.

During free practice on Wednesday, Andretti had heavily crashed his Ferrari. The team chief mechanic, Giulio Borsari, managed to rebuild the car overnight by using the one of Andretti's team mate Jacky Ickx as a reference point with the aid of a local welder. After Andretti won the race, Borsari was awarded the Mechanic of the Race trophy along with a $500 prize.

Hopes for a regular fixture rapidly faded due to financial problems. The Questor Grand Prix remained a one-off event and the Ontario Motor Speedway was never again used to host a Formula One race.

Qualifying
Note: a blue background indicates a Formula 5000 entrant.

1 Hobbs, Lovely and Byers were late entries and relegated to reserve drivers. 2 Stewart briefly drove Foyt's car in qualifying.

Classification
Note: a blue background indicates a Formula 5000 entrant.