Part of it is standards. Europe has the common sense approach, less fuel burned equals fewer O2 emmisions, diesel gets much better mpg, therefor it polluts less. Besides, the USA thinks all diesel engines are like big rig engines with dirty injectors, belching black smoke and making a racket.

My MB diesel doesn't smell, belch black smoke, or make a lot of noise. The 3L engine just produces 395 lbs of torque, not bad when you are in a hurry.

Volkswagen also has a 2L diesel that gets close to 50mpg on the highway.

The problem in the USA is that California and New England have very stringent rules about particulates and have killed the sales of diesels for the rest of us. VolvoNA got rid of the clutch.

Klaus