Before we drove it, the idea of an X5 M seemed outlandish, and we suspected BMW's motives had more to do with marketing than the company's engineering reputation. How could an X5 all-wheel-drive SUV live up to the M badge? We should have trusted BMW, whose engineers are so pure of heart they would never let a vehicle wear the M that didn't deserve it. The X5 M is a monstrously powerful beast that handles like a sports car. In fact, we had to drive up next to other cars for a height comparison to remind us we were in an SUV.