2012 mercedes-benz slk roadster
The newest gasoline engines from Mercedes-Benz feature cutting-edge lean-burn technology that leads to fewer harmful emissions and a 10 percent improvement in fuel economy. Well, the new engine tech, which requires a much leaner fuel-to-air ratio, is making its way into many mills, but apparently not the ones destined for these United States.

Ward's Automotive quotes Daimler powertrain development vice president Bernhard Heil as saying that the gasoline in the U.S. contains sulfur at the rate of 95 parts-per-million; about twice as much as can be tolerated by the new engines. The problem? Excess sulfur apparently clogs the nitrogen oxide-capturing traps.

So, is the U.S. the only country lagging behind Europe in removing sulfur from its gasoline supply? Far from it. Heil points out that the gasoline in Africa and many areas of Asia also contain too much sulfur for the lean engines. The first engine to feature the technology is the direct-injected 3.5-liter V6 destined for the C350 sport sedan and the SLK roadster seen above. The 302-horsepower mill will not (obviously) utilize lean-burn tech here in the U.S.

[Source: Ward's Automotive]