1. Slip lock pliers - need them most trips for water hose connection, as the arthritis in my hands makes it hard for me to tighten it sufficiently.
2. Leatherman.
3. Screw driver with multiple bits in all configurations. The one I have has an LED light in the handle that shines on the business end.
4. Seat belt cutters. Not strictly tools, but every vehicle we own has at least two. Upside down, filling with water or on fire isn't a time you want to be restrained. They clip to the sun visors, and we also have them in the center consoles and the glove box. In the RV we have them clipped to the front curtains. When you need one, you need it now.
5. I'm an EMT, so the cutter I carry in my pocket also has a rescue knife and a window punch.
6. Duct and electrical tape, fuses, DVM, hammer.
7. Work gloves.
8. Gojo hand cleaner.
I love that my Ace has a toolbox area in the top interior step. I can just reach in from outside and grab what I need.