The E53 X5 was available with a 3.0 turbo diesel in other markets (as was just about every other BMW model). While the twin-turbo setup in the US-market E70 and E90 is a few years old, it, too, is under the hood of other BMW models in other markets. Bottom line is that the technology is a very well proven; one would hardly be a guinea pig with an X5 35d.

The 35d may be quiet compared to an American pick-up, but compared to my 2006 MB CDI, the diesel clatter is VERY loud (not that I mind).