A Video has now leaked out of Audi's new monster diesel concept that's going to be revealed at the Detroit Auto Show in just a few days. Audi is taking the 5.5L TDI V-12 they had in Q7 TDI concept at last year's show and stuffing it into the rear end of the R8 sports car. That's a combination that can yield a 0-60mph time of 4.2 seconds with a 186mph top speed on the Autobahn while steel achieving an average of the 23mpg on the EU test cycle. This 500hp, 737lb-ft monster is unlikely to ever make it to the end of an assembly line - especially with the pending EU CO2 regulations and US CAFE standards - but it's still interesting to ponder the possibilities of what a diesel engine can do. Check the studio video after the jump.