The introduction of ultra low sulfur diesel (ULSD) fuels to the U.S. market in 2007 paved the way for American drivers to take advantage of the fuel European drivers had enjoyed for decades.
Diesel had been a mainstream fuel in Europe for a number of years, as the high price of petroleum products over there quickly led to the recognition of the benefits of diesel fuel. A diesel engine typically returns up to 40 percent better fuel economy than a comparably sized gasoline fueled engine.
Ultra-low sulfur content in diesel fuel enables the usage of advanced emission control technologies on diesel vehicles. The combination of ULSD with these advanced emission control technologies is sometimes called "clean diesel." A recently developed process—which involves injecting a chemical called Urea into the catalytic converter—makes ULSD fuels burn cleaner than gasoline.
The vast majority of clean diesel models on sale in the U.S. are German. In fact Volkswagen, Germany’s volume manufacturer, dominates the list of the best clean diesel cars in America with six of the nine models for 2013.