I used to rally a bit way back when my wife found it fun and found that generally you don't have time to fix things properly during the rally and expect that if you can fix an item it will on the side of the road in the rain in the dark and if you can't your car will get towed t the next checkpoint. My longest rally was two days so a four day rally is way beyond my paygrade.
Once the day was over we usually helped participants with more serious ailments than my car so I never permanently fixed items even if I had the time until the rally was over. Most of the problems were related to rocks hitting things, vibrations breaking things off and just pushing the car a bit too much. My list from memory of what I carry in my car for a rally is as follows (this is from memory so I must be missing something):
Umbrella, swiss army knife, rags, toilet paper, duct tape, selfamalgamating tape (plumbing fixing stuff), red vapour barrier tape, bailing wire, metal coat hanger, zap straps (couple really big ones and some smaller ones), mini butane torch, solder, enough wire to get from fuel pump to battery and back, first aid kit, multi purpose tool, needle nose pliers, vice grips, multi driver, continuity tester, voltage tester, air in a can, spark plugs, spark plug wires, distributer cap, fan belt, emergency blanket, silicone, 5 minute epoxy, super glue and baking soda (for gas tank holes) couple small pieces of wooden dowling, few sheet metal screws, nail to puch a hole for the screw if you need, spare lug nuts, tooth picks, tounge depressors, piece of tin foil, matches, shrink wrap, couple baggies, large garbage bag, disposable coveralls, disposable gloves, pencil, paper, flashlight, road flare, a handful of nylon nuts, couple 1/4" bolts and nuts and a tire plug kit. Items like oil and coolant and wd40 are always in my trunk of my car and don't take much room. A full roll of toilet paper takes up lots of room so use 1/2 of a roll and fill center with wire or something.
Most of this fits under the parcel shelf. Put an empty duffle bag in the parcel shelf, spread it out to fill the cavity and then fill up the bag to the max height. That way you can grab the bag all in one piece to help a broken down car.
Always a boyscout.
