Good Question. As some of you have seen, up here in North Dakota we have had some pretty tough weather already that left people stranded in their cars. In the 1980's Fargo had a very bad winter storm that took the town by surprise and there were several people who died within the city limits because they didn't have the correct gear to keep warm. What I keep in my truck is:
1. 2 sleeping bags (rated at 0)
2. 1 wool blanket
3. 1 big coffee can with a big candle (for heat)
4. 1 big coffee can filled with trail mix and candy bars
5. 1 roll of TP (that's year round material)
6. 1 medium size shovel
7. 1 25' tow strap (8,000#)
8. 2 50# sand bags (for weight or traction)
9. 2 flashlights
10. 4 flares
11. I always have my survival pak that I carry in the bush with me in the vehicle. Along with my Bk7/ Bk9.
You can use the second coffee can to melt snow or ice for water. All of this gear fits in my large ruk sak (except for the sand bags).