As stated above, the issue of unexplained opening of windows, sunroofs, rear hatches etc. has been reported and discussed many times. It appears to happen mostly with cars that have comfort access and as far as I can remember, no one has really come up with a credible explanation. Some have suggested that excess water (heavy rain etc) might cause it... I don't know if I believe that. I had comfort access on my 2010 X5d and never had that issue. Just a couple of months ago, I parked my 2012 X5d (with comfort access), went inside for about 30 minutes and came out to find all 4 windows and the sunroof open! I'm 100% sure I did not leave them open. I never leave the car with a single window open, let alone all 4 and the sunroof... It was a sunny day with not a single cloud in the sky. The keyfob was in my pocket but that's where I've always kept it... Go figure!
2010 X5 35d