Consumer Reports is running an article titled, "The alternative cars are coming" - and the diesel-powered Jeep Liberty is mentioned. Here's a snippet:

Over the next year, your choices of alternative-fuel cars will grow significantly with the introduction of two new gasoline/electric hybrids and three diesel-powered cars.

...snip...

Next year, DaimlerChrysler will begin selling two new diesel cars in the U.S., a Mercedes-Benz E-Class sedan and a Jeep Liberty SUV. Both are turbocharged and use a cleaner-burning common-rail fuel-injection system. Next year, too, Volkswagen will introduce a diesel-powered Passat TDI sedan and wagon. Diesels get up to 30 percent better fuel economy than comparable gasoline engines, but they produce more smog-causing emissions than contemporary gasoline engines of comparable size. Low-sulfur diesel fuel, however, is expected to become widespread in the U.S. by the fall of 2006. This will allow diesel engines to be fitted with equipment that will reduce the major pollutants--soot and oxides of nitrogen.

Be sure to check out the entire article.