Based on the sultry-looking Le Mans Quattro concept car presented at the 2003 Frankfurt Motor Show, the production version of the Audi R8 supercar debuted at the Paris Motor Show in 2006. And though the R8 was rolled out a V8 initially, there were rumors from the start that it would see a larger engine made available someday, since the engine compartment had plenty of room to spare. This theory bore itself when a concept car powered by a 12-cylinder diesel appeared in the 2008 Detroit Motor Show, then again in 2009 when a 5.2-liter V10 model, the 5.2 FSI Quattro, entered production.