Built in 1970 by the Questor company, a US conglomerate, the Ontario Speedway cost a remarkable US$25.5m. The track was 3.21 miles in length, following the standard USAC oval configuration, with a road circuit section infield, which would be linked with a section of the banking to provide a Grand Prix configuration. The nineteen turns were numbered rather than named, with the number 13 skipped for superstitious reasons.
The owners persuaded FISA to schedule a second American Grand Prix for the 1972 season at the Speedway. In these times it was standard for a proposed Grand Prix venue to hold a non-Championship race the year before the intended championship event. The Questor group put up a prize fund of $278,400, which raised interest, and also decided to boost spectator interest by opening up the competition to Formula A cars. Formula A was a 5-litre class not unlike Formula 5000 which was moderately popular, ran by the Sports Car Club of America. The 1971 Questor Grand Prix promised to be an exciting event.
the only date available, March 28th, clashed with both Formula One's traditional pre-season Race of Champions at Brands Hatch, and also the USAC round at Phoenix. Despite this, the entry was very good. Scuderia Ferrari sent Mario Andretti, at the time primarily known as an USAC driver, and the Belgian Jacky Ickx to Ontario, both driving the 312B models with which Andretti had already won the South African Grand Prix in that year. The team's other regular driver, Clay Regazzoni, had been dispatched to the Race of Champions. Yardley BRM sent a three-car team, as usual believing in strength in numbers. Pedro Rodriguez was the only driver in the squad the have previously driven the new P160, although a brand new example was provided for Jo Siffert. Howden Ganley was still in the old P153. Gold Leaf Team Lotus were widely tipped to run the new 56B turbine car in the event, but after its disheartening debut at Brands Hatch the week before, the choice was left in the hands of lead driver Emerson Fittipaldi, who opted for the more conventional Lotus 72. Reine Wisell was also despatched by the Hethel outfit with Cosworth's brand new Series 11 variant of the ubiquitous DFV.
McLaren Motor Racing sent a two-car team, with an M19 for Denny Hulme, and an old M14A for Peter Gethin. Matra Sports entered just Chris Amon, in a single MS120B, with a year-old engine in the back. Motor Racing Developments wheeled out the famous lobster-claw BT34 for Graham Hill, while Tim Schenken had to make do with the old BT33. Tyrrell appeared with their original self-designed car, 001, but upgraded with the second series 11 Cosworth, in the hands of Jackie Stewart. STP March sent just Ronnie Peterson after teething troubles with the new 711, withdrawing their other entry. A second 711 was on hand, though, Frank Williams Racing sending along Henri Pescarolo, as well as Derek Bell in an old March 701. An even older 701 (as used by Chris Amon and Mario Andretti in 1970) was entered by STP for reigning Formula A Champion John Cannon. The planned Team Surtees entry of team owner John Surtees and Rolf Stommelen did not materialise, so the final Formula One entry was Pete Lovely in an old Lotus 49B, but he arrived late, and was only allowed in as third reserve.
The Formula A entry was a lot smaller. Lola's T192 customer car made up a large amount of the entries present with new examples going to past champions Lou Sell and Tony Adamowicz, as well as a third being loaned to reigning USAC Champion Al Unser. The prototype T192 was loaned to the Penske team, who entered Mark Donohue in the car. Yet another T192 was run by Bob Bondurant, who had driven a handful of Grands Prix in 1965-66. Charlie Hayes entered two of the older T190s which his team had modified extensively, and with Bobby Unser (a respected USAC driver but had humiliated himself in his one try in Formula One with BRM) and Ron Gable driving. The team also entered Jack Byers in a non-modified T190 as a reserve driver. All were powered by Chevrolet V8 engines.
Two 1970-spec McLaren M10B cars were also there, one for Briton David Hobbs (who had driven in a couple of Grands Prix) and one for the great A.J. Foyt. Again Chevrolet V8s were used, but Hobbs was unfortunately entered late due to a mix-up and was only registered as a reserve. Two Surtees TS8 cars were on hand, one for Sam Posey (who would later drive in a pair of US Grand Prix for Surtees' works F1 team) and the other for Peter Revson (between his two spells in Formula One after an unsuccessful period with Reg Parnell's team in the mid-60s). The final Chevrolet-engined car was a little more unusual. Another past F.A. Champion, Gus Hutchison, was driving the American ASD (Aero Structure Developments). The futuristic-looking car was moulded from unusual materials, and featuring a wing-mounted radiator and rising rate front suspension. Lotus' unsuccessful Type 70 had one entrant, George Follmer (later to dominate CanAm with Shadow and get a year in their Grand Prix car) using a modified Boss Ford engine. The final Formula A entry was Swede Savage, a young American driver under the watchful eye of Dan Gurney, running a 1969 Eagle with a Plymouth V8 powerplant.