It appears to me the people with the most problems are those who number one: perform frequent fluid changes (possibly with the wrong fluid); number two: reprogram or modify their transmissions, and number three: misinterpret worn driveshaft splines or low vehicle voltage as a transmission problem. I think the units are quite reliable under normal driving conditions. However, due to the higher performance characteristics of the X5 itself, many of us take on a more "spirited" driving attitude, thus advancing the normal wear cycle of the driveline. I have 242,000 miles on my 3.0 with a build date of October 2002. The fluid has never been changed and I have done at least 15,000 miles of towing a 1300 pound PWC & trailer in Texas heat with no problems at all.

In past lives with GM turbo 350s, 400s, 200Rs, a fluid and filter change every 30,000 miles was the norm. But with newer synthetic fluids and the precision of electronic controls, the internal wear factors have been sharply reduced.