She drives an 08 Kia Spectra 5 which is well maintained, and it's front wheel drive. The car wears a set of 4 studded snow tires. So there is no need for chains.
She's had no complaints about the roads so far, but we have had pretty warm weather, with temps dropping below freezing only after dark. But she's usually not home until a few hours after dark. So far so good.
And I think because of this she's put the thought of bad weather and wrecks in the back of her mind.
She does have a few things in her car, first aid, Spyderco Native, jumper cables, tire iron/pry bar and a diaper bag

But I will need to throw in water, food, flares, glass breaker and strap cutter. Maybe a blanket or sleeping bag. We all dress correctly for winter, so I'm not too worried about extra clothing, we usually bring changes of clothes for the kids just because they're still little and messy. My wife has put her snow pants in her car though, because she knows that she may have to shovel her self out of her parking space to leave work.
I'm not going to buy wet suits or an oxygen tank.

If I was THAT worried my wife wouldn't be driving. Like I said before, she's worried about going off a bridge and getting the kids out. Which is pretty silly because she dries a very light weight car and I don't think she'd be able to make it through the guard rails. So the strap cutter is mostly for her piece of mind.
The rest of the stuff is more practical I think.