There is a well known formula used by offroaders to calculate the insidence of BMW X5s on there roofs at the first sign of snow
Fact is many people buy a 4x4 firstly because of the perceived pose value, secondly the perceived safety factor and lastly, for the winter.
Many of these 4x4's are fitted with high performance, low profile, fat road tyres that offer very little straight line grip in snow, let alone lateral grip. When braking, due to the weight of your average 4x4, they offer very little stopping power in slush and on hard packed snow. Drivers should be aware of this, but many havent a clue about tyres.
As some of you know I am a bit of an offroad enthusiast (I have stables to keep my landrovers in..lol) and currently am driving a Subaru Outback in an out of work because it behaves much better on hard packed snow than a Landrover does. Much better feedback, lower centre of gravity and fancy electronics keep me mostly on the straight and narrow
For really deep snow a Landy comes out
Over the years I have had to pull quite a few 4x4s out of ditches/off of slippy patches and without exception they were driven by people who turned around and said, "but its a 4x4, I expected it to be better in the snow than it is"....and without exception, they all had high performance road tyres fitted to fat alloys.
Round my way Subaru rules supreme..and for jolly good reason