Soft plastic, like one-use water bottles, don't crack but the frozen water inside is not immediately available to drink either. Quicker to melt snow in an emergency than wait for clear hard block ice to melt in the car. Hard plastic will split open and steel will split or warp if left in the vehicle overnight. I have several 18 oz Kleen Kanteens (which are always in a neoprene insulated sleeve) that I had to pound the bottom back in with a hammer so they would stand on end again. I have a small pot and an Esbit stove in the back just in case. In wintertime in this climate (-10 F and breezy this weekend) , staying warm and having suitable spare outerwear, footwear, hats, gloves, is more important than food or water for the short term.