Audi's latest Le Mans challenger, the R18, has been revealed as a coupe.
The car, which will replace the Le Mans-winning R15-plus, was unveiled at a launch in Ingolstadt tonight.
The R18 will be powered by a 3.7-litre six-cylinder turbodiesel and will soon begin an extensive testing programme.
Audi's motorsport chief Dr Wolfgang Ullrich confirmed that the latest Le Mans rules led to the switch to a closed car, following rival Peugeot's lead, after a decade of open Audi LMP designs.
"The rules mean you have to have a roof to be competitive," he said. "Driver changes are always easier with open cars, but the changes have taken that away.
"The smaller capacity engines [turobdiesels have been reduced from 5.5 to 3.7 litres] also make aerodynamic efficiency more important.
"It breaks my heart because I love the open cars, but the expectations we have of this car are very high and it looks great."
Although Audi did not rule out introducing hybrid technology in the future, Ullrich reaffirmed the firm's commitment to using a turbodiesel.
"We believe the TDI engines are the most efficient, so it was very clear that we would use them at Le Mans," he said.
Audi confirmed it will contest the Sebring 12 Hours with the R15-plus, ahead of the R18's debut at the Spa round of the Intercontinental Le Mans Cup in May. It will then be used at Le Mans, the Imola 6 Hours, Silverstone 6 Hours, Petit Le Mans, and China 6 Hours.