Both are great trucks, 3.0 or V8.
For me, I don't really "use" the V8 power more than 30 seconds per day... merging, first at a stop light, or just having fun.
Sometimes I think... why do I suffer w/ 16 MPG?
A couple of reasons... the rumble of the V8, the sound under acceleration, the torque, the fact that I can tow if I need to. Beyond all of those "practical" reasons, there are much bigger underlying emotional reasons why I went for the 4.6...
Knowing I have the most bad ass X5 available, knowing I have one of the rarest X5s available, and knowing that I have one of the best performing SUVs around.
It's worth nothing on paper, but it's worth a whole lot when you get it and your face lights up.
Boys with toys....