Is this to bug out or just escape for a weekend?
From memory in my truck:
1. Get-me-home-bag (similar to bug-out bag but designed to get me home from work)
2. Maps of Houston, Dallas, Texas and the surrounding three states in each direction.
3. USA/Canada/Mexico road atlas
4. hygiene kit (toothbrushes, antipersperent, toilet paper, seat covers, comb, soap, wash clothes)
5. Coveralls plus change of clothes
6. Tools (regular tool kit, air compressor, tire pressure gauge, jumper cables, etc...)
7. Big first aid kit (though mainly filled with gauze and bandages)
8. Extraction tools (come-along, tow strap)
9. Two extra large spraycans of fix-a-flat
10. assorted flashlights
11. AA-powered, waterproof radio
12. spare batteries
13. small folding stool (actually in house awaiting repairs right now)
14. assorted paperback books and magazines
15. deck of cards
16. tarp
17. ropes of assorted sizes and materials
18. spare diapers and baby wipes (note to self: replace diapers with larger size!)
19. Stuffed animal (monkey)
20. folding saw
21. water
22. assorted tie-down straps and bungie cords
23. mess kit and canteen

There's more, but that's the main stuff.

-Blast