Wife and kids were rescued form the car, dad went looking for help and died.
Driving through snowy mountain passes means taking the right gear: snow chains, blankets, power bars, water, extra clothes if the starting and stopping destinations really aren't that cold.
Even in the Northeast when you really arent that far from civ. (ever) if you're in a car in the winter it makes sense to throw a sleeping bag and some extra warm clothing in the car. If you break down on the side of the highway and have to hoof it somewhere I would rather do it in some warm hiking boots, etc. then in a business suit.
But I feel bad for the family. It's a sad story.
Also good for any vehicle is first aid kit, flashlight, knife, road flares, some extra vehicle fluids, and length of line (rope).