One problem related to alternator/generator/regulator has been reported for the 2002 BMW X5. The most recently reported issues are listed below.
I've had to replace all 4 window regulators, my rear hatch seems to open for no reason, my rear window wiper is working with the switch in the off position, led's are going out again and now the dreaded apparent oil seperator with tons of grey smoke billowing out the back of the car after being left in an airport parking lot for 4 days whilst it snowed outside. Seems I've had every typical problem other than the car catching fire for no apparent reason. I have owned Bmws in germany and the us for a long time, however, I think I'll be switching brands with my next vehicle. BMW doesn't seem to be proactive enough for my liking with some of these way too common issues. This is a very low mile vehicle for it's age and it's acting like a model t.