We recently returned from a jaunt in the USA. A gallon of regular gasoline ran about $2.55. At these prices, I don't think there would be a lot of demand to justify the expense of certifying diesel engines and training dealers to service them. Diesels are cool but they come at a large price premium over gasoline engines. Besides, diesels have never sold in much volume in the USA, with the notable exception of heavy duty pick up trucks.