More than just sulfur. Most importantly centane index! American diesel's centane index is a lot lower than the European diesel. The American VW TDI diesel would be only an average diesel engine in Europe. I know Audi has a diesel which you probably could not tell the difference between it and a gas engine untill you had to refuel. The European diesels are very quite, very fast and quick, and very fuel efficient but requires a much higher centane index than what American diesel has. If you do not believe me, just get one of those high performance European diesel engines and but American diesel in it.
