I feel the X5M is two different "cars". With M-mode off and in normal transmission the X5M drives very civilized. Difficult to get any speed out of it because the transmission is always up shifting for fuel economy. You really have to stomp on the pedal to get it to down shift three gears to get the speed.
Turn on M and put it sport. It will be fast! I feel it is a little sneaky fast. You just don't recognize how fast you are going. Look down and you are doing 130 at the end of the on ramp trying to merge into traffic. Not sure if it is because it is smooth with its power delivery or because you are sitting up higher or what.