Here are some tips on surviving a snowstorm in your car.
If you are stuck in the snow, it is safer to just stay in the car. Unless you have a nearby building or business that is open, and, you can see it clearly is within walking distance.
You should not keep the engine running. You may run out of gas. Better to start and run the car every 20-30 minutes, then shut it off. Never sleep with the car running. Check to make sure that the exhaust pipe is not blocked by snow. You may get carbon monoxide poisoning.
Without the car running, you need to keep warm anyway you can. Wrap yourself in anything available in the car. It is warmer inside the car, even without the heater. You can move around a bit to warm yourself up. Move your hands, clap, stretch, do some arm exercises, etc.
Do not use your cellphone unless you need to. Save the battery life.
Drink any water you have, but melted snow will cool you down.
If emergency personnel show up, follow their instructions. Getting your car out of a tow yard is better than freezing to death.
If you do get unstuck, and are able to drive again, be careful. Go slow and stay in a low gear, even with an automatic transmission. If you have antilock brakes, you can brake harder, but you should still tap them lightly as well. Be careful of bridges and other black ice situations. Another reason to slow down or not drive at all. You need to be aware of snow plows and ice trucks. Don't block them or you may get a ticket. Also do not stop in the middle of an intersection. Avoid hills with ice.
Stay safe by staying off the road!