According to Car and Driver, there are only two new cars in the U.S. market into which one can introduce diesel fuel without provoking costly damage: the $51,825 Mercedes-Benz E320 CDI and the $22,235 Volkswagen Jetta TDI. When 2007 rolls around and more stringent emissions requirements finish phasing in, we may find ourselves with just the Benz. Mercedes has shown us its particulate-filter-equipped and 2007-compliant E320 BlueTec, but Volkswagen hasn't revealed what it's doing to comply with the stricter standards.
Presumably, VW will follow Mercedes and add similar technology to clean up the exhaust; however, VW has conceded that a 2007 diesel Jetta might not be ready here by the beginning of the year. If VW diesels are your bag, you're not entirely out of luck. The German automaker may stockpile 2006 Jetta TDIs, which it will sell into the 2007 calendar year until a true, emissions-compliant 2007 model is ready.
2006 VW Volkswagen Jetta Owners Manual