BMW is coming out with a tri-turbo diesel engine (http://www.bmwcoop.com/2009/05/06/new-bmw-tri-turbo-diesel-engine/) for the X5, and it will then be available on the 6 and 7 series also...
What's your opinions about that engine? :)

It's good if you want to tow things around all day. Other than that, the engines doesn't really serve any other practical purpose.