I remember reading an article in Popular Science when I was a kid on how to use the materials in a car to survive. All I remember is the headliner and insulation from the roof and seat materials can make a makeshift coat, and the oil from the engine makes a great smoky fire to help rescuers find you.
When I was doing field work years ago, I always traveled with the kit you describe. In addition, I tossed a sleeping bag in the trunk, some canned food and a few cans of sterno. Luckily I never needed it.