Freeze dried food makes sense in applications where weight is critical - typically when backpacking or use in a plane, etc. Other wise, FD is expensive and requires extra time to prepare. Since it lacks moisture, it is probably more resistant to some degree to the high heat of a car interior. I don't really know; I keep my stash of FD stored in ideal, cool conditions. My car has tasty supermarket items that I rotate from time to time. Remember, in a real tight situation, gourmet standards will lower considerably.