Don't forget a poly tarp. It has lots of uses:

You can use it to throw on the ground so you don't get your clothes dirty/wet if you have to kneel for a tire change or crawl under the vehicle.

You can throw it over you and the whole end/side of the vehicle so you can change that flat in the rain without getting soaked.

You can rig it up to provide shade if you break down and have to wait for help.

If you come upon a collision where someone has died, is covered in blood, or dismembered, you can cover the body to spare the rubberneckers the unpleasantness of viewing the body. Children especially don't need to see that sort of thing.

Sorry to be so graphic. <img src="/images/graemlins/frown.gif" alt="" />