Mercedes-Benz bills its ML320 BlueTec as the cleanest diesel in the world. It uses AddBlue technology, a urea solution which, when injected into the exhaust stream, converts nitrogen oxides into ammonia. Mercedes-Benz will also launch BlueTec versions of its R-Class and GL-Class.
Shown at both the Detroit and Frankfurt auto shows, the S300 Bluetec combines an economical 2.2-liter four-cylinder diesel engine with a small, 15kW electric motor for extra boost. Mercedes says it will be compliant in all 50 states, but don't expect it to arrive here before 2012.
Having knocked the auto world's socks off with the gasoline version of its twin-turbo-charged 3-liter engine in the 335i, BMW is planning a diesel sequel with the 335d. The new engine, which won the 2008 International Engine of the Year award, dishes up a whopping 425 pound-feet of torque at just 1,750rpm. The 335d will be launched in all 50 U.S. states in the fall of 2008.
The 2008 Volkswagen Touareg 2 comes with the option of a massive 5-liter V-10 diesel, serving up 310 horsepower and 553 foot-pounds of torque. Its 15mpg city/20mpg highway mileage is disappointingly low, but what do you expect from a car that can tow a Boeing 747 jumbo jet?
Audi also claims the title of the world's cleanest diesel for its new diesel engine, found in the A4 TDI. According to Audi, the diesel A4 achieves a 35 percent improvement in fuel economy compared with the 3-liter gasoline model. Already on sale in Europe, the A4 TDI is slated to make its way to the United States later this year.
Although it wasn't officially announced during this year's auto show season, a diesel version of the Acura TSX is likely bound for U.S. showrooms in 2009, possibly as a 2010 model. Similar to the diesel version of the Honda Accord currently on sale in Europe, the diesel TSX will probably be powered by Honda's 50-state-compliant 2.2-liter turbocharged four-cylinder iDTEC engine.