Audi has unveiled its entry for the 2011 endurance racing season, a hard-top V6 turbodiesel that (finally) looks like a proper Le Mans car.The R18 has been designed to defend the brand's 2010 Le Mans victory against arch rival Peugeot and comes with a closed cockpit design (like the 908HDi Peugeors) and a much smaller engine. The new Le Mans LMP1 class rules have dictated a shift in design priorities with engineers seeking to gain a performance advantage in terms of aerodynamic efficiency instead of a balance of engine power and endurance – something Audi has been particularly good at with its powerful (yet frugal) turbodiesel engines. SMALL V6...The 3.7-litre turbocharged compression-ignition V6 has only half the cylinders of the original R10 V12 and also manages to be appreciably smaller in terms of engine architecture than its direct predecessor, the R15 V10. To compensate for the peformance discrepancy of a much smaller engine, Audi’s aerodynamicists were given free rein to design the most intricate shape imaginable. There are a vast number of ducts, wings and specially-shaped composite surface details to ensure the R18 manipulates the air it cuts through it in a manner making it as quick (and stable) as possible. Plainly, with the closed-off cabin and more radical aerodynamic surfacing than a contemporary fighter jet - the R18 looks like a proper modern-day re-incarnation of those classic Group C endurance racers of the 1980's. Around the rear of the car is what appears to be a neat Red Bull-like F-duct system. ...REALLY (REALLY) BIG LEDsThe R18’s most notable design feature (other than, well, its design) is a pair of oversized LED headlight clusters, the most elaborate use of lighting diodes yet seen in circuit racing. What else would one expect from a manufacturer that has made the proliferation of LED's part of its road-car design signature?Audi Motorsport Wolfgang Ullrich says the R18's been designed for "progressive" electrification, which would probably be engineered in the form of some sort of energy recovery system. Although the R15 will spearhead Audi’s endurance racing assault at the first major event of the 2011 season (Sebring), expect the new R18 to debut in May at the Spa-Francorchamps Six-Hour.