I always keep a pair of wool blankets behind the seat in my pickup truck, along with an old rubberized army poncho. They stay in there year-round. Plus a small tool box, jumper cables, log chain, tire chains, hitch pins, several sections of rope, and several chunks of canvas. The first-aid kit and fire extinguisher also always stay in there. In winter I also add a pair of pull-on rubber overshoes/boots, a rolled up insulated coverall, plus mittens and stocking cap and scarf. The back of the pickup gets a pair of 10 gallon milk cans full of sand tied in by the tailgate - for extra weight/traction. And a can of wood stove ashes to spread on ice for traction - far better than sand. Some people put a bag of cat litter in - the clay sticks to ice better than sand. Plus the usual vehicle jack, but I also have a hydraulic bottle-jack in there as well - and a farm high-lift jack in the back. And always an iron scoop shovel - not those cr*p pieces of aluminum they call "snow shovels" and sell to city folk to clear their 20 to 30 feet of sidewalk and driveway.
But when I drive anywhere during winter, I also DRESS APPROPRIATELY!!!!!! I've seen way too many people dress like they were going to step into a nightclub and then drive off into a raging blizzard! They deserve whatever troubles they may encounter. For me it's rubber boots or insulate pack boots, heavy coat, possibly an insulated coverall, hat, scarf, and GLOVES!!!!!!! I've got friends who know better who consistently leave their gloves at home - even when temps are 10 below zero (F)! And then they whine about cold fingers, or freezing, or getting snow in their shoes.
I always plan on the possibility of a couple mile walk - in case something happens while driving in the winter. And I've had to assist far too many clueless people who had vehicle problems out in the winter snows. But I also live at least 20 miles one way from town, and many of the farm places around here no longer have anybody living there. So waiting for somebody to happen by to help me is not a good option. Another vehicle might not travel any road for a few hours to several days!
That piece of hand-held ear jewelry (a cell phone) would be nice ... sometimes. But I don't own one. And there are many places around me where they just don't work or get a signal - including my home valley. They are too flaky for me to ... rely upon ... in any emergency.
I always have some bottles of water in the truck, and occasionally some food. But I usually grab some of each when I head out to the vehicle.
But I tend to be more prepared than most. SO be it. Better safe by my own hand than end up on the evening news. I ain't waiting for anybody else to come along to save my sorry behind. Too often that ends up being TOO LATE!
Mikey - that grumpy ol' German blacksmith out in the Hinterlands
p.s. Even those couple years when I lived in a city and drove a car, it was packed in a pretty similar manner during winter - and year round.