We have a 2001 X5 3.0i. 239,000. It's been very well behaved, apart from the oil separator. I think this was a BMW joke. Sorry BMW, not funny. Rear suspension bushes will soon need sorting. One air spring burst at about 220,000. Iffy pixels. That's it.
Also 2001 X5 4.4i. Bought cheap with bad water leak from rear of engine. Whoops! Was on l.p.g so brilliant and cheap. Leak was valley pan. Had been "repaired" with bathroom sealer, not silicone. New part from BMW cheaper. It eat it's timing chain tensioner and developed a serious oil leak from the sump. Gearbox can judder a bit, but must wait until summer now.
My wife says I have a problem as I also have E38 750, E34 540 touring, E36 318i touring on lpg and a too new 2012 320d. Not a problem, surely?