After a year-and-a-half of development Audi Sport have unveiled the R18 – the new car the German marque hope will bring them their tenth victory in the 24 Hours of Le Mans, when the new car is charged with defending their title.

The most striking element of the new car, when compared to the R8, R10 and R15 that have gone before is that the R18 is a closed coupe design – Audi's first since the R8C in 1999.

“In the future, aerodynamic efficiency will be even more important at Le Mans than it was in the past,” says head of Audi Motorsport Dr. Wolfgang Ullrich. “A closed car has clear advantages in this respect. Our computer simulations have been confirmed in the wind tunnel and during initial track tests.” The car also features the F1-esque shark fin mandated on LMP1 cars under the new regulations for 2011.

However, while much has changed for the new car some things remain the same. The 3.7 litre, V6 engine will be diesel powered, Audi continuing to mine the diesel concept they introduced to Le Mans with the R10 and now defines the race at the front of the endurance event. The smaller engine has also necessitated the development of a new gearbox designed specifically to work with the powerplant.

Also new to Audi's Le Mans challengers is the use of the same sized wheels on the front and rear of the car – a concept that was recently seen on the Acura LMP1 of the 2009 ALMS season.

In other areas Audi engineers were able to take advantage of the experience garnered with other cars in other racing series. The company highlight this fact with the development of the heated windscreen and ventilation systems for the new car, falling back on the knowledge from Audi's DTM program as well as the R8C and the closed coupe of sister brand Bentley that won at Le Mans in 2003.

The Audi R18: Daytime lights designed to form a 1

Interestingly Audi say the R18 was “designed for progressive electrification”, clearing the path for hybrid versions of the R18 in the future. “Efficiency is always the crucial factor for us,” says Dr. Ullrich. “No matter which form of energy recovery we may choose the key aspect for Audi – in motorsport as well as on the production side of the house – is that it provides a true advantage.”

The new car will make its racing debut at Spa-Francorchamps on May 8, though Audi plan to take part in the revived Le Mans test day, which will allow the new car its first sighting of the Circuit de la Sarthe.

Three R18s will be entered by the works Audi Sport Team Joest squad at Le Mans, with the same driving squad as brought home the 1-2-3 finish of 2010. Also confirmed was a two car entry in the seven event Intercontinental Le Mans Cup.

However, while all the interest was (understandably) around the new car Audi's racing rear will begin without it.

Instead of the R18 two “R15 plus plus” cars will hold the four rings flag at March's 12 Hours of Sebring after the firm were absent from the event in 2010. “Sending the R18 into a race at such an early point in time would be difficult in terms of logistics and interfere with our development program,” Dr. Ullrich explains.