FOR MORE CAR VIDEOS & REVIEWS CHECK OUT http://www.kbb.com/kbb/NewsAndReviews/VideoLibrary.aspx Audi R8 V12 TDI. A diesel-powered exotic car can't be any more preposterous than a diesel-powered racecar, right? Featuring a 6.0-liter, twin-turbocharged V12 variant of the V10 diesel powerplant used in Audi's Le Mans-dominating race cars, Audi claims the R8 V12 TDI concept car will reach 60 miles per hour in about four seconds on its way to a top speed around 185 mile per hour. Even with more than 500 horsepower and 700 pound-feet of torque at its disposal, the R8 diesel can reportedly return highway fuel economy in the low 20-mpg range -- while Audi's "AdBlue" urea injection enables it to pass rigid U.S. diesel emission standards. For more new car reviews, interviews and automotive news visit kbb.com today.