New Mercedes Diesels Ruled Illegal in Five Key State

The soon-to-be-launched and much-hyped Mercedes-Benz E320 Bluetec has reportedly failed to meet emissions criteria in the important states of California, Maine, Massachusetts, New York and Vermont.

Mercedes said its E320 CDI was the cleanest diesel vehicle in the world, but apparently not clean enough for U.S. regulators.

Despite their popularity in Europe, diesels have never been commonplace in the United States and have a reputation as a technology for big rigs only. But there's a more ecological explanation for the lukewarm reception. Diesel is actually more harmful to the environment than gasoline because it generates more nitrogen oxides (NOx), gases that play a major role in the formation of acid rain and haze.