I don't have experience with X drive. I suspect that if you live in a long Northern winter snow area X drive might be more beneficial because of the variables rather than fixed 60-40 split.

On the other hand, having grown up in Michigan on Lake Michigan where there is plenty of lake effect snow I think getting around on ice and snow is far more dependent on experience and tires.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas