I just returned from my first trip in my new 2008 X5 4.8i. I put on about 2000 km through the Rocky Mountains between Alberta and BC in Canada. The X5 handled great and had more than enough power for passing on the sometimes narrow mountain roads. I had rain and some very light snow for almost all of the trip but, alas, no ice to test out the DSC system. I love the X5 and everything worked great. Only beef I have with the unit is the *&^%$#@ running boards. They are almost impossible to use and I still haven't figured out a way to use them when getting into the X5 without craking my head or getting my pant legs dirty.
In the Garage:
2001 330xi Orient Blue on Gray
2006 M5 Interlagos Blue on Black
2008 X5 Space Gray Metallic on Black