Where does a company go after the wild success of an LMP car like the R8? Back to the drawing board, coming up with a revolutionary diesel-powered Le Mans Prototype like the R10 TDI. And the R10 TDI was even more successful than its predecessor, a remarkable accomplishment in its own right—the car won every single Le Mans race it entered outright until it was replaced by its successor, the R15 TDI, in 2009. Under the composite bodywork is a 5.5-liter V12, using twin-turbochargers and direct injection to make an estimated 650 horsepower. While this is a ton of power, the R10 TDI’s true advantage is better fuel economy and massive torque, generously available. Whatever the reason, Audi’s open LMP car became the dominant force in prototype racing until its retirement. A quick spin will show why—wickedly fast and producing massive downforce, the car is a real competitor. This car, #2, won the 2008 Le Mans outright with Rinaldo Capello, Allan McNish, and Tom Kristensen behind the wheel.