I would have the 5 most common socket sizes for your car, in 3/8" drive.
a ratchet, 3" and 6" extentions
a set of channellock pliars
1/4" screwdriver bits, in the most common sizes and types you need
1/4" bit driver handle
an adjustable wrench(2 sizes, a small 6" one and a 10" one
medium vice grip pliar
Dont forget to carry the right socket/breaker bar combo or lug nut wrench for your car!
I dont know much about your car, but a set of fuses, some bulbs, duct tape, a cuple hose clamps, some silicone sealer,zip ties and a flashlight could be a Huge help!
I know it's more than 10, but i like to be prepaired for anything.
I carry a full set of metric and inch wrenches up to 19mm, 3/4", socket set in 1/4" and 3/8", screwdriver and bits, ratchets, extentions, 3/8" ujoint,slip joint pliars, needlenose and wire cutters. flashlights, tape, gloves, hoseclamps, etc.
and i;ve used them all. I was the only person at at an FFA dinner that had any tools, used most of them trying to fix this girls car that broke down. Spent 2 hours troubleshooting in a the parkinglot.