Yeah, I don't understand the mpg of the European diesels. On the one hand, people claim BMW MB VW etc in Europe sell incredible luxury performance turbodiesels that get 50 mpg. On the other hand, when they bring these vehicle to the US, the mpg is nowhere near the hype.
http://www.autoweek.com/article/20081111/FREE/811119977
BMW on Tuesday released fuel-economy and pricing details for its upcoming diesel versions of the 3-series and X5. The diesels will be shown at the Los Angeles auto show next week, ahead of their launch in the U.S. market.
The sedan, badged the 335d, is rated at 23 mpg in city driving and 36 mpg on the highway, bettering original estimates. It will cost $44,725, including destination charges when it arrives in December.
The X5 xDrive35d is rated at 19 mpg in the city and 26 mpg on the highway. It will sticker at $52,025, including destination when it arrives in January.
So something isn't adding up. Either BMW's engineers are morons, or the dieselers' hype is overblown, or something else.
I do note that all lot of the hype "mpg" claims use Imperial gallons, which are 1.2 US gallons, thus overstating mpg by 20%. 35 mpg (US gal), overstated by 20%, becomes 42 mpg.