It should come as no surprise to learn that Europe and the U.S. has different fuel standards. I never realized how different though. Apparently the 95 parts per million sulfur content in U.S. pump gas is too much for the new Mercedes engines to handle. These new engines operate on a much leaner air/fuel ratio, which is to say that there is less gas mixed in with the air during the combustion process, resulting in a cleaner burn and improving both horsepower and fuel efficiency.
The problem is that these new engines require a trap that captures oxides of nitrogen that are later burned off separately. These traps can be poisoned by any sulfur content above 50 ppm, which means Mercedes is unable to send these more-efficient motors to America. One of these engines was the new 3.5 liter V6 (pictured above) which has 302 horsepower and a combined gas mileage of 21 mpg (though up to 31 mpg on the highway), which is a substantial improvement in power and efficiency over the outgoing engine. Alas, until America cleans up its gasoline, such high-efficiency Mercedes engines will remain out of reach of our American dollars.
Source: Wards Auto
Chris DeMorro is a writer and gearhead who loves all things automotive, from hybrids to HEMIs. You can read about his slow descent into madness at Sublime Burnout or follow his non-nonsensical ramblings on Twitter @harshcougar.