Originally Posted by Weasel

Think of it like this, the X6 is to the X5 what the E63 6 series coupe is to the E60 5 series.

It is a better handling, more powerful, more sporty version of the chassis for those that don't need the 4 doors and want more fun from the platform. I personally like the E60, but love the E63. Like the E70, but love the E71. It becomes more "enthusiest" and less "practical". It is for the love of driving it!