Audi and Peugeot have both criticized new rules that could result in significant changes to the balance between gasoline- and diesel-powered prototypes ahead of the Le Mans 24 Hours.
Their criticism follows statements from the Automobile Club de l'Ouest that it is looking to invoke a new article in its rulebook to make changes between "different fuel types" on the evidence of the cars' performance at the Sebring 12 Hours and the opening two Le Mans Series rounds. It has insisted there will be a level playing field for the 2011 24 Hours.
Audi Sport boss Wolfgang Ullrich said: "We produce our engines for Le Mans in March and April. If something is decided after that, we cannot react."
Peugeot Sport technical director Bruno Famin suggested that the policy could result in sandbagging.
"If the regulations are changed after three races," he said, "everything that happens before could be fake."