I bought my 2005 X5 4.4i last Friday and we were right in the middle of a long below average very, very cold week here in Montreal. When I say very cold, I mean -25 to -30 degrees celsius (without the wind chill factor). I drove my X5 for a 1000 km in this freezer and I had no problem whatsoever. No door stuck, no weird engine noise, just a little hard time to defrost the back windows, that's all. I'm crossing my fingers it'll stay that way.