John S. 
2007 BMW X5 SUV 4.8i 4dr SUV AWD (4.8L 8cyl 6A)
BMW X5 vs MB GL450
 The X5 with the V8 has nice acceleration and a throaty growl.  The ride is noticeably harsher than our MB GL450 and neither really exhibits excessive body roll. On worn highways I often try to drive to the side to get a smoother ride.  I really regret getting the side aluminum running boards, they make it much more difficult to get in and out.  While many reviews say the iDrive is easy to learn, I sure wish BMW would add more dedicated buttons.  The GL450 is much easier to use to access the map, radio, etc.