Audi R15 TDI

The Audi R15 TDI, commonly abbreviated to the R15, is a Le Mans Prototype (LMP) racing car constructed by the German car manufacturer Audi AG. It is the successor to the Audi R10 TDI. Like its predecessor, the R15 TDI uses a turbocharged diesel engine, although the R15's V10 engine is physically smaller than the R10's V12. The smaller engine is pushed further toward the middle of the car than in the R10, resulting in a more neutral weight balance that gives the car better agility around the corners than its predecessor.

The car was tested for the first time in December 2008, before its official unveiling and competition debut at the 2009 12 Hours of Sebring race, 21 March 2009. Three R15 TDIs participated in the 24 Hours of Le Mans in June 2009, under the control of Joest Racing. Audi did not defend their American Le Mans Series, or Le Mans Series titles with the R15 TDI.

The R15 made its competition debut at the 2009 12 Hours of Sebring in March 2009, and followed this event at the 24 Hours of Le Mans in June. The R15 got off to a perfect start by winning the 12 Hours of Sebring, setting a new race record in the process, but then lost in its second entry. Peugeot, its rival, with its 908 HDi FAP, took the top two spots in the 24-hour race, ending Audi's five-win streak that lasted back to 2004 with the gasoline-powered R8.

The R15 TDI features a 5.5 litres (336 cu in) Turbocharged Direct Injection (TDI) turbodiesel V10 engine, rated at over 600 PS (440 kW; 590 bhp) and 1,050 newton metres (774 lbf·ft) torque. The electrical system uses a lithium-ion battery, a first for Audi sports prototypes, as well as LED headlights, and a unique system of LED rear lights that are mounted on the rear wing endplate.

In the week running up to the 2009 24 Hours of Le Mans, rivals Peugeot lodged a protest against the R15, claiming that its bodywork did not comply with regulations stating that parts of the bodywork cannot be fitted with the sole purpose of generating downforce. However, after the Wednesday free practice session, the ACO rejected Peugeot's protest. At the 2009 Le Mans, Audi was unable to continue its winning streak that dated back to 2004. The #3 R15 ran off at Indianapolis corner, and the #2, driven by Luhr, crashed and retired. In the evening, the #1 Audi lost a lap to the leading Peugeot which was faster, and further technical issues dropped it a full 7 laps down the order. The sole surviving Audi clinched a podium finish, finishing in third place.

Audi announced on August 25, 2009 that two R15s would race at the 2009 Petit Le Mans. Both Audis led for approximately 90% of the race but a late spin during the final rain-soaked caution handed the victory to one of the Peugeot 908 HDi FAPs entered by Team Peugeot Total. This loss was Audi's first since competing in Petit Le Mans since their initial attempt at Road Atlanta back in 2000.