Since its first attempt in 1999, Audi has won the Le Mans 24 hour race nine times with the R8, R10 TDI and R15 TDI, equaling Ferrari’s all-time win record. Last Friday it unveiled the new R18, a closed carbon fiber monocoque coupe specifically developed for Le Mans with a 3.7-liter V6 TDI engine and another first for endurance racing – all-LED headlights.

Recognizing that aerodynamic efficiency will be even more important at Le Mans than it was in the past, the new R18 marks the first time since 1999 that Audi will contest the world’s oldest endurance race with a closed coupe. Unlike that of the closed Le Mans prototypes, which consisted of two halves, the carbon fiber monocoque chassis of the R18 features a single-component design that reduces weight and increases stiffness.

The chassis and aerodynamics of the R18 take much of their inspiration from the R8, the R10 TDI and R15 TDI, however the fitting of identically sized front and rear wheels, which allows for a more balanced weight distribution, is a first for an Audi Le Mans sports car.

With rule makers looking to achieve a substantial reduction of engine power in 2011, significantly smaller engines than those used before will be prescribed. This has led to Audi retaining the diesel concept that saw its first victorious outing in 2006 with a 3.7-liter V6 TDI unit with a six-speed transmission that has been specifically modified for use with the smaller engine.

Another first for the new R18 is the inclusion of all-LED headlights. Aside from optimizing the amount of light produced at night, during the daytime the LEDs form the shape of a “1” which is apparently intended to “inspire associations with Audi’s historic brand logo.” The company says the next generation headlights will also be prepared for future use in production vehicles – although the “1” formation seems unlikely to make the transition.

Development of the new R18 started in mid 2009 and the V6 TDI engine has been running on the dynometers since the summer of 2010. The car itself completed its first test on a racetrack at the end of November with its racing debut planned for the Spa-Francorchamps 6 Hours in Belgium on May 8, 2011.

Prior to that, the new R18 prototype will do its first laps on the Le Mans track during the official test day on April 24, 2011, to gather data ahead of the race on June 11 and 12, where Audi is planning to field test three R18 cars, which will be entered by Audi Sport Team Joest.