Gareth,
One of the reasons folks in the US have been reluctant to buy diesels in cars is the horrible experiences had with the domestic manufacturers previous attempts to market them in cars. Some were merely converted gasoline engines that lacked the necessary strength in the bottom end. All had problems - those that bought them felt burned, and knowledge of the problems was well spread. Now there are younger car buyers that don't have the bad taste in their mouths, so diesels are probably once again a marketable option.