No X6 diesels for the US Market. You can however watch them get built and roll off the assembly line in SC
There are lots of threads about the options and/or packages that are must have. Mucho discussion. Here are the facts..
1. The vehicle does just fine with the i6 and probably handles better with it.
2. The gas mileage with the i6 is better, although not crazy better, just a bit.
3. The sound of the V8 is amazing. One poster said his X5 50i sounded better than his X5M in almost all conditions. It is intoxicating and I honestly upgraded to the V8 for the sound alone. I LOVE IT.