Le Mans 24 Hours organizer the ACO has further restricted the performance of the diesel-powered prototypes in an attempt to bring them into line with the quickest gasoline-engined cars.

Audi and Peugeot's diesels dominated last month's Sebring 12 Hours, which although an American Le Mans Series round, is viewed as a dry run ahead of the Le Mans 24 Hours in June, prompting the ACO to further peg back their advantage over the gas cars.

The diameter of the fuel flow limiter of the diesel cars will be reduced from 38mm to 33mm – the same size as the gasoline cars – and an additional 30 kilograms of ballast will be added to each diesel car. The changes will be introduced for the Le Mans Series's Spa 1000km race on May 10.