I found my X5 to be a great cold weather car, down to -30, which it saw several times. Only problem I had was the inside rear windows icing up at those temperatures, as there wasn't enough heat getting to the luggage compartment.

When it is really cold, the air is usually drier. The problems mentioned above are from temperatures closer to freezing, and condensation related to continuous heat/cold cycles. That comes from short trips.

The issue isn't cold weather, it is that BMW designed these cars to be driven. They need to get hot, and be run hard, regularly. If not, you pay the price.

And warming it up in a driveway is the absolutely worst thing you can do for them. That doesn't warm the vehicle up at all, as there is no load on the engine. What it does is just prolong the cold engine operation, accelerate engine wear, and contribute to further problems.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue