I keep a wintertime emergency pack in the trunk of my car, right next to the snow shovel, plug in [to the cigarette lighter] tire pump/air compressor, [a couple] old bath towels, a roll of TP (wrapped in plastic), camping bow saw and a couple 2 liter PET soda bottles sorta full of drinkable water.  The pack has a couple good-sized candles, a Bic lighter and a pack or two of matches, some bandaids, adhesive tape, gauze pads, a wire survival saw, some extra bootlaces, tinfoil, hard candies (butterscotch and peppermint swirlies), a couple envelopes of hot chocolate mix and of oatmeal, some teabags, a couple envelopes of instant soup, a little heat-tab stove and fuel tabs, a clean old soup can and one of those blue-enameled camping coffee cups, and a camping knife-fork-spoon set.  While there's a lot of stuff, it all fits inside a little surplus backpack about the size of a big set of binoculars.

Winter can be rough here and, if a traveler gets in trouble, it can be lonely for a long time, too.  When I moved here, one of the things I brought back was the winter emergency pack for the car.  

To that I recently added a cheap pocketknife and whistle, tied to opposite ends of a lanyard, and a pack of replacement fuses for the car, particularly the 20Amp size that power the cigarette lighter.  They cost like 79 cents for a pack and are the size of a matchbox.  But, without them, you always run the risk that the air compressor will fry the fuze and leave you ... stuck.  Cheap prevention.  And I'm going to add a couple of the bandannas the dog groomer ties around the dog's neck when sending her home after a clip and wash.  They're the right size for slings, tying on bandages and making bindles.