NASCAR vs. IMSA: How the “Match Race of the Century” Played Out

NASCAR owns IMSA, and it’s been that way since 2012. But there was a time when IMSA owned NASCAR (not literally, though) in a particular race that panned out between two of the greatest motorsport athletes. The race was even called “The Match Race of the Century”.

Back on April 24, 1974, a piece was published by Speed Sport which was titled, “NASCAR Bows to IMSA”. The final rumble at Road Atlanta was between John Greenwood, driving his IMSA Corvette, and Bobby Allison of the famous Alabama Gang, driving his Permatex 200-winning Chevrolet Camaro, holding the banner of NASCAR.

Unfortunately for NASCAR and Allison, Greenwood defeated the veteran racer by a margin of 6.7 seconds. According to him, Allison had missed out on shifting the gear at an extremely decisive moment, and after that, he was nowhere close to even tailing Greenwood.

Ecstatically, Greenwood said, “The Goodyear people told me to be in guard. Bobby put on trick tired just before the start.”

How are NASCAR and IMSA cars different?

One glance is enough to realize that the IMSA sports car and the Next Gen stock car are two entirely different breeds. The NASCAR car uses 18-inch wheels and a V8 naturally aspirated pushrod engine to ensure cooler running than the forced induction ones. And this is the standard for every car that runs throughout all three national series.

However, there are six different classes of cars used in the IMSA. Among them, the Daytona Prototype International (DPi) stands out; despite using the same Michelin tires as others like the Le Mans Prototype 2 or the Grand Touring Daytona Pro, the DPi class can choose between hard and medium compounds.

The next difference is in the power of the engine. While the NASCAR machine aims at a horsepower of 670 (which is reduced at Atlanta and the superspeedways), the IMSA prototypes target an HP of 600 and feature a six-speed sequential transmission. Moreover, unlike NASCAR, IMSA cars use V6-V12 engines.

There’s more. While NASCAR uses cars from three manufacturers, Ford, Chevrolet, and Toyota, IMSA has 18 manufacturers across all six of its classes; Acura, Alfa Romeo, Aston Martin, Audi, BMW, Cadillac, and Lamborghini, to name a few.