Since most our rigs have plenty of gear, we need to make sure the alternate vehicle also has an appropriate kit. I was on a trip to LA when our car started to have problems and lost power in the middle of the California desert between LA and Las Vegas. We coasted down the ramp in the middle of the night on - and I shit-you-not - Old Ghost Town Road. We limped into a closed service station with no one around.
While the problem was serious and required parts and a mechanic to fix, the fact that we had food, water, charged cell phones, a good flashlight, and an OBDII code scanner made it possible to get help, wait comfortably, and better understand that this was not a field-fix problem. The bandage was also helpful when I cut my hand trying to reach into the engine bay without due care. By the way, the PTU of the AWD shat the bed and had to be replaced. We had to complete the trip in a rental car and come back a week later to retrieve the car from the shop.
Mostly my kit helps others. Whenever it snows I end up pulling cars out, last season it was a lady who got off into some deep, heavy slush (not typical for us) and managed to high-center her sedan. People were trying to push her out, but without wheels on the ground, that wasn't going to happen. I pulled her back to a plowed lane with my recovery strap.
I also have used my tow strap to drag wrecks out of the road.
You can't see it in the image, but the transaxle case was cracked and it puked all the ATF out onto the road. I was already removing the car from the highway by the time Highway Patrol arrived on scene. I was careful, a guy in a construction truck with lots of flashing lights closed the lane so I could work safely.
EDIT:
I just remembered two stories from a while ago, I didn't think of them because I didn't have an overland rig at the time.
Back when I was 16, I came upon a motorcycle crash; the pillion rider had passed out and fallen off the back of the bike mid-corner and was unconscious in the middle of the road. I pulled out a towel, first aid kit, and road flares. I treated the rider for shock, deployed flares around the corner, and got someone on the phone with 911. I ended up staying with the rider and helping EMS with the IV, got her on a backboard, and helped load her in the helicopter.
The second major incident was in California. A truck carrying a shipping container crashed on an overpass in the MacArthur Maze (big interchange in Oakland by the Bay Bridge). The container detached from the trailer and came forward, partially crushing the cab of the truck. The cab ended up teetering on top of a concrete wall about 80' off the ground. I was there before EMS, so I stopped to help. Two other truck drivers also stopped, one had a big prybar we used to open the door. Normally I would never move someone who had suffered trauma, but we were worried about losing the entire rig over the side. I treated for shock, assessed for TBI, and stopped the bleeding. I pretty much depleted my tiny first-aid that I kept in my Civic. Fire arrived and took over, they also replenished my first aid kit and let me wash my hands with the fire engine.
After that I decided that drug-store first aid kits are garbage and I built my own into an ammo box. Now I have a big fold-flat bag that is all nicely organized - and I make sure to keep some Israeli field dressings in there along with a ton of big gauze pads. I'm not going to be caught short on supplies ever again.
