My alternator went at 126,000 miles. I'm in Texas so the electrical load is typically from A/C use, and the fact my CEO likes her seat heated almost all the time no matter what the weather.

I've also had one tensioner replaced at about the same mileage, but never any issue with the fan clutch.

2002 X5 3.0 246,300 miles
2004 325i 110,000 miles