CarbonFibre

What are the emissions differences between the US and Europe that make bringing TDI cars over here such a pain? Also, is high sulphur content the only fuel problem or are there other issues?

badgerh

Teh rimary issue is NOx emmission. The regulations require very low levels, particularly in some states like California. Current diesel technology has no chance without some specific add-on technologies. The cheapest is urea injection in the exhaust. It looks like mercedes will go with this for their 50 state approved diesels. If this is the case and the authorities allow it (problem is that you need to refill the urea tank and that not doing so has no effect on performance) or put some interlock to disable the car when there is no urea, then I expect that Audi and others will follow.