Wow. I don't recall ever hearing of that!
The dude (cop?) stuck in his car for days surviving on "snow and cigarettes" was pretty famous.
That is a pretty important story. Especially for you folks who live in a snowy climate. My dad had to travel by car up there the for his business. He taught me something that I still do and the only snow I ever really see is when I go up to a Browns game.
In the winter, toss a good blanket and some warmer shoes and socks in the trunk. Takes up very little room.
Also get a metal can and stuff it with 5-6 tea candles and fire source for heat. The can becomes a vessel for melting snow and or containing the burning candles. You also stuff the can/cans with things like smalls bags of nuts, candy, jerkey, etc....anyting you think you might need for a few days.
A couple of coffee cans and a blanket and such won't stuff the trunk, but will come in handy if you end up having to hunker down for several days the side of the road.
