[Guess]

Here is the thing.

Most RWD cars, even with snow tires, are crap in the snow and ice (ex. mustang) The reason behind that, is because the manufacturer of those vehicles isnt as anal as BMW. BMW has put in so much thought and engineering in their vehicles, its not even funny. the car has even 50/50 weight distribution, which accounts to why the vehicle is so great on any road condition.

I have driven fwd cars, rwd cars(and trucks), awd cars(and trucks) and nothing compares to how my bmw handles ice and snow combined on winter tires.

The only thing thats better in the snow (deep snow) then the bimmer is my jeep, but that thing is 4wd, short wheelbase and sitting on 35x12.5" tires.

So ya, with a bmw, the rwd=sucks in the snow is very much over rated.