Back in the 70s, I had a one man 'resident office' as an Army/DoD special agent, from mid 71 to 74 at Grand Junction, CO; and late 74 to 80 at Dugway Proving Ground, UT. My issue vehicle at Grand Junction was a Ford Sedan and later, at Dugawy, a Chevrolet. Anyway, among my survival info was a brochure from Bureau of Land Management (BLM) which explained how to burn a motor vehicle in a survival situation. The brochure assumed you were snowed in or blocked by an avalanche on a mountain road/wherever and still had an operable vehicle.
The first step, and in line with other posters, was to consider the vehicle as a shelter. Here were the steps as I recall them 40 years later:
1. You're blocked. You can't go ahead or back. What to do? If your vehicle is driveable, go onto the shoulder and scrape away the snow, etc., to bare ground. Back the vehicle over the bare ground, get under it, and puncture the gas tank with your lug wrench, knife, whatever. Let the gas drain onto the bare ground.
2. There'll be enough gas left in the carburetor to start the vehicle and drive a few feet forward. Ignite the gasoline where you just drained it.
3. While the gas is burning, get your spare tire out and deflate it. NEVER try to burn an inflated tire which can explode! Put the spare on the burning fuel, then take your jack and lug wrench and dismount the other four tires/wheels. Deflate them and stack handy for burning.
4. As one tire is consumed in the fire, add another. When you get down to one or two left, rip out your seats, overhead, door panels, etc. Anything that will burn and have ready to add to the fire.
5. As I recall the phamplet, you can keep the flammable parts of the average sedan burning for a full day or more.
This does a couple of things for you: One, the fire provides heat/comfort. For two, it provides a hell of a cloud of black smoke so potential rescuers can find you.
I never had to do this but I kept it in mind as I was running the back roads of western Colorado, eastern Utah, northern NM, and southern Wyo for several years.
I was caught in one avalanche south of (a town I won't name) and shot the phone lines down with my trusty sidearm. Ha! Here came a Bell truck with snowplough on the front within an hour or two. The crew wasn't too happy with me but they did understand my situation. I was able to drive back the way they had come, make a 100 or so mile detour and finally get home.