5 clean diesels: The future is now

Stick your nose an inch away from the exhaust of the diesel-powered ML320 CDI, a vehicle that has been on sale in most states since 2007. Expecting stink and soot? All you get is a warm, odorless, NOX-laden air. The 2009 ML320 BlueTEC eliminates even those nitrogen oxides. The BlueTEC system injects urea into the exhaust stream. That turns NOX into ammonia which is changed into nitrogen and water vapor in a catalytic converter. Refuel from a pump that has never carried high-sulfur diesel and it will stink less than gasoline.

The ML320's turbocharged diesel will produce 210 horsepower and about 400 pound-feet of torque. Highway mileage should be about 25 miles per gallon. Other versions of clean diesels will appear in Mercedes R- and GL-Class vehicles.