On March 28, 1971, a grid of formidable open-wheel cars lined up on the starting grid of California’s Ontario Motor Speedway for one purpose: To put Europe’s Formula One cars against those of America’s Formula A (also known as Formula 5000). That race was called the Questor Grand Prix.

The Questor Grand Prix was designed to be one of the many ways to create interest in European open-wheel racing and to establish Ontario Motor Speedway as one of America’s finest tracks. It remains the only venue in history that hosted racing events sanctioned by the FIA, USAC (for IndyCar), NASCAR, and the NHRA thanks to its road course and oval.

As a way to garner attention for the track, race organizers wondered what would happen if nimble Formula One machines took on the brawn of America’s Formula A series. It was set to be the “richest road race ever staged in the United States,” the Modesto Bee reported on January 12, 1971, with a purse slated to exceed $250,000, or about $1,775,000 in today’s money.

The race was invitation-only, so only the best of the best could compete. In order to compensate for the different builds of the vehicles — specifically the smaller gas tanks of the Formula A machines — organizers decided the race would be held in two heats of 32 laps or about 100 miles, with the final winner decided by aggregate time.

The News Journal in Wilmington, Delaware invited racer Mario Andretti to write his own column about the event predicting what he foresaw happening:

There are some who are inclined to think the Formula A machines will be quicker on the straightaway. Someone else will probably give the Formula One cars the edge going into the corners.

From my experience, I think the Formula One car will be superior all the way around. I could be wrong, but if I am, it will have to be proven to me.

Andretti continued on to explain the difference between the two series. Formula A machines were a little heavier with their five-liter engines; Formula One, on the other had, had a maximum displacement of 181 cubic inches. Or, as Mark Donohue put it in The Unfair Advantage, “I decided that the greatest difference between Formula A and Formula 1 was that their motors had three liters and cost $20,000, while ours had five liters and cost $5,000.”

When it came time to race, though, the turnout wasn’t quite what organizers had hoped; plenty of Europeans turned up with their vehicles from the already-started F1 season, but the American racing season hadn’t yet begun, leaving them on the back foot. David Hobbs would go on to win the Formula A season in 1971, but he submitted his entry for the Questor Grand Prix too late to be admitted. Indy 500 winner A.J. Foyt, along with many other Americans, failed to find a good ride and ended up with whatever he could get. And then there was Gus Hutchinson, who got behind the wheel of a car that had never turned a single lap before.

At the end of the day, the Questor GP boasted 38 competitors on the entry list (though Jackie Stewart was listed twice; once for Elf Team Tyrrell and once for Agapiou Brothers/Young American Racing). Four of the entrants did not show up for the event, Stewart didn’t start in the Agapiou car, and three others failed to qualify for the final starting grid of 30 cars.

The Formula A drivers that qualified included:

: Sunoco Penske Racing: Brian O’Neil Racing: Champ Carr Inc.: STP Corporation: Smothers Brothers Racing Team: Charlie Hayes Racing: Competition Developments: Milestone Racing Team: American Racing Associates: Kastner Brophy Racing: Charlie Hayes Racing: Aero Structures Developments: Junior Tarozzi Racing/Keith Black Racing: Agapiou Brothers/Young American Racing

Meanwhile, these were the F1 drivers that turned up:

: Elf Team Tyrrell: Equipe Matra Sports: Scuderia Ferrari: Bruce McLaren Motor Racing: Yardley Team BRM: Motor Racing Developments: Yardley Team BRM: Gold Leaf Team Lotus: Gold Leaf Team Lotus: Scuderia Ferrari: Motul/Frank Williams Racing Cars: Motor Racing Developments: STP March Engineering: Yardley Team BRM: Motul/Frank Williams Racing Cars: Bruce McLaren Motor Racing

Both heats were dominated by eventual F1 World Champion Jackie Stewart, but Mario Andretti managed to pass Stewart both times to win by a significant margin: three seconds in the first heat and 12 seconds in the second. He came away the winner, followed by Jackie Stewart, Denis Hulme, Chris Amon, and Tim Schenken in the top five. The best-finishing Formula A driver was Rob Grable in seventh place, followed by Lou Sell in 13th and Mark Donohue in 14th.

Despite the hefty prize money and the promise of two distinct formula series competing against one another, the 1971 Questor Grand Prix was destined to be a one-off event. The race drew a mere 55,000 fans, and despite Ontario Motor Speedway’s ability to host countless racing events, the track never quite established itself with any sanctioning body. It was demolished 10 years later.

The Questor Grand Prix may simply have fallen victim to circumstance. The Formula A cars simply weren’t fast enough to compete against the F1 machines, though a formidable competition could have been staged a few years later, in the mid 1970s. Formula One, too, had no idea how to break into America in any tangible way; the success of Watkins Glen was always tenuous, and the politics of international competition and expectations were always complex. Unfortunately, that was the last time F1 cars took on American open-wheel racers in competition.