2010 Audi R15 plus – click above to enlarge

Testing for the 24 Hours of Le Mans doesn't begin until mid-June, but that doesn't mean that Audi isn't already hard at work bettering the chances of their diesel-powered R15 TDI racer.

Thanks to a belated rule change for the LMP1 class designed to hamper the dominance of diesel-powered vehicles, Le Mans rulemakers have mandated smaller-diameter air restrictors and curbed supercharger pressure in an effort to level the playing field. According to Audi, those alterations have made the German automaker prioritize aerodynamics and downforce even more than normal.

The result? Audi boffins have completely re-engineered the front-end of the car, so much so that the new split nose racer has been designated "R15 plus." The updated LMP1 entrant has already begun testing its new aerodynamics, revised cooling and fuel tank systems in the United States, and further testing in Europe will follow before the legendary French enduro. Audi says that the 5.5-liter engine continues to crank out upwards of 590 horsepower. Can't remember what last year's R15 look like? Compare and contrast by clicking here. Official press release after the jump.

[Source: Audi]
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2010/03/15
Audi banks on efficiency at Le Mans

# Evolution of R15 TDI diesel race sports car
# In-depth testing program in the United States and Europe
# TAG Heuer is new Audi partner in LMP1 project



Ingolstadt, March 15, 2010 – Audi will fight for victory in the Le Mans 24 Hours on June 12/13 with an evolution of the R15 TDI diesel race sports car. An extensive testing program with the revised LMP1 vehicle has just begun in the United States.

"From Audi's perspective, the LMP1 is the better alternative to Formula 1 because this motorsport category features technologies and developments which are relevant to production vehicles," explains Head of Audi Motorsport Dr. Wolfgang Ullrich. "At Le Mans, efficiency is of paramount importance – and today, more than ever before, it is a key deliverable of production vehicles as well and it is one of Audi's special strengths."

Therefore, efficiency was a focal point during the R15 TDI evolution project – particularly in the complex area of aerodynamics. "This year, the Le Mans regulations prescribe air restrictors with a smaller diameter and reduced supercharging pressure for diesel-powered vehicles," says Dr. Martin Mühlmeier, Head of Technology at Audi Sport. "Due to the reduction of engine power as a result of the regulations we have tried to make the car's aerodynamics even more efficient than before and to improve the Cd value and downforce parameters."

A late change in regulations that was announced only in November made the work of the engineers more difficult and forced Audi to completely modify the front section of the R15 TDI. Consequently, the diesel race sports car that is internally designated as "R15 plus" now has a new, distinctive face featuring a split nose.

The entire shape of the R15 TDI's body has been revised for maximum efficiency. The same is true for the modified cooling and fuel tank system. The V10 TDI engine has been optimized for the smaller air restrictors and reduced supercharging pressure. "Our objective was to keep power loss to a minimum despite the limitations imposed by the regulations," explains Ulrich Baretzky, Head of Engine Technology at Audi Sport. "We managed to do that through a lot of detailed work." The 5.5-liter power plant continues to deliver more than 440 kW.

"After Le Mans 2009, our specifications for the R15 plus listed about 20 key items," says Dr. Martin Mühlmeier. "Efficiency and reliability were at the top of the list but we also looked at details like improved nighttime lighting of the track. We were able to meet this wish of the drivers with a new headlight concept."

The evolution version of the Audi R15 TDI completed its roll out on the Audi test track at Neustadt (Germany) on March 3. The vehicle was subsequently flown to the United States for two weeks of in-depth testing. Before the race at Le Mans in June, Audi Sport Team Joest will complete an extensive testing program on various European race tracks and test races at the 8 Hours of Le Castellet (France) on April 11 and at the 1000-kilometer race at Spa-Francorchamps (Belgium) on May 9.

A new partner has now joined the project: the logo of the renowned watchmaker TAG Heuer will be featured on the Audi R15 TDI. Some of the brand's fame stems from U.S. actor Steve McQueen wearing a TAG Heuer watch in the movie "Le Mans."