For the car trunk or the truck bed, I keep a box of saltine crackers and a jar of peanut butter. We always take water bottles in the truck cab with us, so I don't stock those separately (they would freeze here in Colorado). Then of course the shovel, kitty litter, recovery strap, etc. to get unstuck from the snow. If the trip will take us outside of the urban area (open highway, etc.), then sleeping bags, wool balaclavas, and heavy rag wool mittens go along in addition to our normal winter wear. I've been meaning to buy me a few of those Nuwick candles to take along, but it always seems the online S&H charges to buy those are higher than the cost of the candles themselves, so I've been putting it off searching for a local supplier or some online place with reasonable S&H charges.