Because Europe is a lot smarter than the US when it comes to fuel.

Diesel is just now starting to catch on in the united states. Up until recently diesel was only used for large trucks, semis etc.. Aside from a few exceptions.

__________________
Current Bimmer
2004 X5 4.4i Sterling Grey Sport/Premium

Past Bimmers
1991 318I Alpine White
1995 740I Alpine White
1991 525I Schwartz
1998 323IS Scwartz
2004 330CI Cabrio Titanium Silver Metallic
1995 540I Schwartz
2000 Z4 3.0 Titanium Silver
2000 330ci Coupe Titanium Silver