I have a Ranger pick-up with a FG tonneau cover over the bed. It's really a two seat car with a big trunk. I store a lot of my camping gear in the back including 15 deg mummy bag, wool blankets and tent. I also keep a couple MRE's water and cold weather clothing. My get home walking kit (similar to what many would call a BOB) has additional gear.

I live in SOCAL and my body has acclimated to the nice weather here. When it gets cold I feel it and if I happen to be traveling through the mountains of CA, OR or WA, it can get very cold (and wet). At any time, my truck and I can handle anything from the mild/warm weather of the SOCAL coast to the Washington Cascade Mountains in January. Overkill? Probably, but I need to store that stuff someplace. Don't do Death Valley. . .