Subzero temps are dangerous. Frostbite, hypothermia, wind chill, frozen, frozen, frozen EVERYTHING! What if, God forbid, you got stuck on the side of the road? Yes you would call for help but you should still have some things in your car, a "winter go bag" if you will. You should have bottled water, blankets, boots or sneakers in case you have to walk, a good pair of gloves, snack foods (obviously pre-packaged, non-perishable things like trail mix or granola bars). Put it all in the bag and leave it in the car in case of emergencies or if you get stranded somewhere. STAY SAFE!