I have some of the aluminum water packs in my car. No problem after 2 winters in Detroit. As for food, my MRE is still edible after a few years in the car (Missouri and Michigan weather). I wouldn't leave them more than a few years though. Other options include granola/power bars, Datrex or Mainstay bars, the aluminized-packs of meats found in the grocery store. Again, I've tried all these after months to years, and never really had a problem.