Volkswagen showed off its Touareg TDI at the 2008 Los Angeles Auto Show, billing it as the world's cleanest diesel. The Touareg is powered by a 3-liter, turbocharged, V-6 diesel engine that uses a particulate filter and a solution called AdBlue to break down nitrogen oxide emissions. In the Touareg, this engine makes 220 horsepower and 405 pound-feet of torque, delivering 17 mpg city and 25 mpg highway.
Audi also launched its Q5 TDI, using an engine similar to the Touareg TDI's, at the 2008 Los Angeles Auto Show. In the Q5, Audi tunes the engine differently so that it produces 240 horsepower and 368 pound-feet of torque. Smaller than the Touareg, the Q5 TDI returns 21 mpg city and 28 mpg highway.
Audi sponsored a 4,888 mile cross-country marathon, inviting journalists to drive different legs of the route and compete to get the best mileage. The Mileage Marathon included diesel versions of the Audi A3, A4, Q5, and Q7. The A3 TDI scored 50.6 mpg, the best mileage in the marathon, while the Q5 TDI achieved 38.5 mpg.
Volkswagen entered a diesel-powered vehicle in the grueling Baja 1000 offroad race. Although it looks like a Touareg, this car has a custom-built platform with a mid-engine layout. This engine is also much bigger than the 3-liter V-6 in the production cars, although it uses similar technology. The engine is a 5.5-liter twin turbo V-12 TDI, making 550 horsepower and a stunning 625 pound-feet of torque.