I'm going to suggest a different "kit" you might keep in your car--a breakdown/you can't fix it kit.
A few years ago there was an accident on the interstate south of Madison. It shut the whole thing down and people were forced to stay in their cars overnight. It got me thinking: if that happened to me, would I be ready to deal with it? Answer: no.
I've also seen people spun out of the roadway in a ditch in the winter; what if you're stranded there?
So I began thinking about it, trying to figure out what I might want or need in such a circumstance. Further, I live in Wisconsin; if I were stranded in an isolated area with no way to get help, what could I do? And what if it was wintertime? Thus the focus on things that might not appear to make sense if you live, say, in Florida.
I was a boy scout, you know their motto: Be Prepared.
Thus, I am. This kit is in my car and my wife's car, and both my kids have them in their cars. The kit includes $30 in cash in case the credit card/debit card system goes down and we need cash to buy gas. Or work a vending machine. Or whatever. It includes wire I could use to fix a hanging piece of exhaust system, duct-tape a loose fender in place, and so on.
So...consider a car kit, but not necessarily for repairs. Here's what's in mine:
GEAR/MISC
1. Package of Sharpie pen, some 3x5 cards, folded over pad of paper.
2. Multitool (Plus one in Glove Compartment)
3. Folding knives, (2)
4. Playing Cards (if you're bored; don't wear out cellphone battery w/ games)
5. Aluminum Foil, two squares
6. Hi-Visibility Vest
7. Flares, 3 (can be used to help start a fire if needed) (in wheel well)
8. Fix-a-Flat (in wheel well)
9. Jumper Cables (in wheel well)
10. Money--Four $5 bills, five $1 bills, $5 in change.
11. Four shop rags (red--on purpose)
12. First Aid Kit, includes Ibuprofen and Naproxen Sodium (Aleve)
13. Toilet Paper
14. String backpack (in case you need to move)
FIRE
1. Firestarting kit--Matches, 2 Lighters, Firesteel, Vaselined Cotton Balls.
2. Fatwood (for starting fires)
3. Firelighting squares
4. Plank wood, split, lining bottom of bag, for making fire.
5. Small bag of Popsicle Sticks (can be split smaller)
6. Folding Saw
7. Tealight/votive candles (for firestarting, thawing frozen water bottles)
PROTECTION FROM ELEMENTS/WARMTH
1. Bandana (headcovering, dust mask, tourniquet)
2. Gloves (3 pair)
3. Space (reflective) Blankets (2)
4. Six emergency candles, six Tea Light Candles, 2 Votive Candles
5. Handwarmers, 6 pair, in mylar w/ O2 absorber to keep fresh
6. Rain Ponchos (2) w/ hood
7. Small Blue Tarp (6x8)
FOOD/WATER
1. Granola Bars (Clif Bars)
2. Mainstay Lifeboat Rations
3. Water, bottled, in
1-gallon ziploc bags (6 bottles)
4. Candle Stand for thawing or warming water bottles.
REPAIR/RIGGING
1. Duct tape (8 yards wrapped around a pencil)
2. Paracord (50')
3. Zip Ties (7")
4. Zip Ties (14.5")
5. Electrical Tape
6. Wire, 16 ga., 50'
LIGHT
1. Extra Batteries (both AA and AAA)
2. Flashlight, Keychain LED (w/ solar recharge, in foil and wrapped)
3. Flashlight, incandescent
4. Flashlight, LED, 2 (one is in Glove Compartment)
5. Headlamp (LED
I also keep a blanket in the car in the winter, and if I'm traveling any distance boots and hats and gloves and such will be part of what I have with me.
The tarp can allow you to close off some of a van to reduce the area you might heat, or to provide a privacy screen for you-know-what.
Anyway, you might consider a different kind of kit.