We’ve been waiting for years now for new clean diesels from a number of different manufacturers, including Mercedes-Benz, and finally the German luxury brand is bringing 50-state BlueTec engines to the U.S. in its lineup of SUVs.
Debuting at the New York auto show in BlueTec guise are the 2009 GL320, R320, and face-lifted 2009, all boasting the AdBlue urea injection technology that cleans up the exhaust from the 215-hp 3.0-liter turbo-diesel enough for these diesels to be certified for sale in all 50 states. Currently, these models can only be sold in 45 states.
Urea—a nitrogenous compound found in mammal urine but also produced synthetically—is the BlueTec solution to the last emissions hurdle facing diesel engines in the U.S. Various catalysts and filters have reduced particulate emissions—the heavy black soot associated with diesel engines—to acceptable levels, but until now emissions of nitrogen oxides (NOx) have been too heavy for full 50-state certification. AdBlue is a urea solution injected into the exhaust stream that, when it reacts with the nitrogen oxides, breaks them down into nitrogen and water. The storage tanks for AdBlue should usually only need refilling every 10,000 miles, which will be done as part of Mercedes’s regular maintenance.
With the fuel-economy benefits of diesel—typically 20 to 30 percent higher than comparable gasoline engines—Mercedes is claiming a range of 600-plus miles for each of these three SUVs, meaning that road trippers will likely be stopping to drain their own urea tanks more often than to fill the fuel tank of their Benz.
