When Audi wanted to showcase its TDI diesel technology, it chose to compete in the 2006 Le Mans 24-hour race with a diesel-powered prototype. It was a risky move, as the R10 TDI replaced the all-conquering gasoline-powered R8 that had five straight wins under its belt. The success of the R10, and later the R15, proved that Audi was right. Read more »