I run my current (and ran my past BMWs) on snow-covered roads, with either grit or salt spread on the roads at times.

The biggest problem is rock chips to the painted front surfaces, or losing a windshield. I have never had problems associated with salt on the roads, or the cold. My lowest recent temperature was last year, -30C; it was -17C here yesterday, and it is snowing heavily now.

There have been problems with modern BMWs with the cold, most obviously the crankcase ventilation valve/oil separator, which can freeze up if too much condensate collects in it. Stopping condensate from collecting prevents the problem. Batteries can go after 5 years or so, as the cold is hard on them. Other than that, the vehicles do fine. Germany is pretty close to being a nordic country, at least in weather terms.

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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