Do you mean, for you, or the car? These days, Im not sure what you possibly take to repair a car that breaks down. Aside from flat tires, low oil, or a dead battery, anything built after about 1990 is way too complicated for anything like a field repair.
What you need to do is ensure your own safety and increase your chances of being found. Everyone remembers the sad story of the Kims, the California family that got stranded on a remote Oregon road nearly a year ago. James Kim died walking for help after spending more than a week in the woods. His wife and two daughters survived.
So, if I were packing a car with the remote possibility that I got stuck someplace, Id probably pack something like this (and Im assuming you already have warm clothing with you):
Two gallons of water.
A dozen energy bars.
An inexpensive synthetic sleeping bag rated to 30 degrees or so. Or, an Adventure Medical Heatsheets Emergency Bivy ($15; rei.com), a very compact bag that radiates body heat back to the wearer.
Some kind of waterproof shoeL.L. Beans 6" Bean Boots ($75; llbean.com) are perfect.
A hatchet, plenty of matches in a plastic bag, and maybe some wax-based fire starters.
A high-visibility orange tarp, about 8X10. Good for many things, and will help air searchers spot you.
A bright flashlight and spare batteries. Pelicans M3 2370 LED ($50; pelicanproducts.us) is an excellent, reliable choice.
A dozen auto flares.
That should all fit into a plastic box in the trunk or someplace. And while it wouldnt guarantee youd be comfortable, it would sure raise your odds of survival. Oh, and dont forget this: Tell people where you are going and stick to your plan! Thank you.
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