OK, but as a counterpoint, on our last road trip with our SUV, fully loaded and cruising at 120 km/hr through the Rockies, we got 30 mpg (Imperial). OK, so that is an X3 and not an X5. But it also isn't a diesel, and it doesn't have direct injection or a turbocharger (both of which would help mileage, whether it was diesel or gasoline). It also has the bonus of a manual transmission, which the diesels can't get. I got to use cheaper fuel, and didn't have the oily smell when filling it up. It accelerates quicker than the X5 diesel. It only tows 3500, not 6000 lbs.

My point is that vehicles need to get much better fuel efficiency. Putting a diesel in an overweight vehicle justs makes it a mediocre performer. If manufacturers would make lighter vehicles, diesels would make sense as part of that equation. What the X5 diesel is doing is allowing those who are in love with large bloated sport utilities to hang on to them for a few years longer.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue