I have this in my car in case I break down. I hope I never have to use them because if I do it would be in a emergency type situation.

I have used mylar "space" blankets for the past 30 years for near innumerable projects. Want to make a solar oven? here's a tool to allow that. Increase the rating on your sleeping bag by 20 degrees (put the mylar INSIDE the bag), I've made emergency ponchos from them while backpacking. Ground cloths, signal devices, sun awnings (in this mode they help provide cooling), insulation for coolers, animal shelters, a lining for an incubator.

They don't have to wait around in your car or "read bag" to find uses! However, I carry them in each vehicle, I have one in each of my various (depending on purpose) "ready bags", in emergency kits made for the kids and in all the first aid kits in the house, vehicles, the ranch and other such haunts.

This little piece of plastic may well be one of the premier tools of all time.

If you are setting up a "grab & go" pack - the kind of thing that lives in your car or at your office, insurance against a manmade disaster like a terrorist attack or a runaway nuclear reactor; or a natural catastrophe like an earthquake or a hurricane - you cannot get along without these mylar blankets. You can use them as blankets, cloaks, tents, groundcloths and signal panels. They are almost weightless and as noted, very versatile. They belong in every survival kit, automobile glove compartment, and hiker's pack. I cannot recommend them highly enough.