Group C

Broadly similar rules were used in the North American IMSA Grand Touring Prototype series (GTP).

While the consumption requirement meant that cars needed to conserve fuel early in the race, manufacturer support for the new regulations grew steadily with each make adding to the diversity of the series.

In addition, all races were to be contested over at least 1000 km — usually lasting more than six hours — so it was possible to emphasize the "endurance" aspect of the competition as well.

Eventually, several other makes joined the series, including Lancia, Jaguar, Mercedes, Nissan, Toyota, Mazda and Aston Martin.

This was intended for privateer teams and small manufacturers and it limited cars to a minimum weight of 700 kg and a maximum fuel capacity of 55 liters.

Alba with a small, lightweight turbo, Tiga, Spice and Ecurie Ecosse with Austin-Rover and later Cosworth-powered cars were among the most competitive in this class.

[citation needed] When C1 cars were found to be breaking over the 400 kilometres per hour mark at Le Mans' Mulsanne Straight — the WM-Peugeot recorded the highest 405 km/h (252 mph) during the 1988 event[3] — the FIA revolutionized the class by attempting to turn it into a formula series to replace the C2 category (after they proved to be unreliable at endurance races)[citation needed].

Nevertheless, the race still witnessed protests against the new state of affairs, as spectators placed cloth banners in fences expressing their feelings[citation needed].

The 962 was subsequently banned; the Toyota was later given a special dispensation to race in the Suzuka 1000km, and a few C1 racers were allowed to compete in the newly formed Japanese GT Championship — this would be its final year of competition.

The FIA's Group C formula was designed primarily for the World Endurance Championship which included the 24 Hours of Le Mans.