I have a Sterilite hinged top "File Box" plastic tote that I keep in my cargo area. Like
THIS that I keep some things in. Current list is:
5.11 Tactical "Light for Life" - No batteries (uses 3 small capacitors), takes 60 SECONDS to charge and then has 1 hour useable light (then just another 60 sec.) Can be hard-wired in to vehicle as no batteries means no over-charging (the instructions actually recommend it be kept ON the charger 24/7 when not in use) - Strobe feature works wonders for attracting attention or warning others - Great, great purchase IMO -
THIS ONE
12V Air Compressor -
THIS ONE
Jumper Cables (I took a bathroom type travel bag and put it in there for neatness)
Craftsman 1/2" Breaker Bar
Harbor Freight 37 pc. Impact Set -
THIS ONE - I got it for only $25 and it's well worth that, quality is far from USA made but also pretty far from the usual HF ****, highly recommended for a car kit, comes with a fairly sturdy case as well.
Hats and gloves in the winter - Good quality, warm, gloves.
Work Gloves - Currently MIA, I need to replace them ASAP
200/400 watt power inverter - Enercell brand, it was cheap but it's held up quite well.
1 gallon gas can - empty, but if I ever run out, I can avoid paying $13 for one at 7-11
Roll of paper towels - cuz changing tires can get messy and I keep my car clean
30' Tow Strap w/ hooks
2" Reciever mounted 'D Ring' Tow hook -
THIS ONE - May be an HF special, but I only need it to save me from calling a tow truck once and it's paid for itself ten-fold
Reflective Safety Vest - Can often be found for free, and why not?
Bottle of Washer Fluid - Has come in handy more than once.
Hand Sanitizer - I just always have a bottle or two of this around.
Zip Ties - A dozen 10" cable ties are cheap, compact, and can save your ***.
To clarify, the impact set, fluid, and air pump are stored under my passenger seat. Overkill? Not IMO. I've had it happen more than once that I've wanted/needed an item like this but it's been in the garage.
On my list to add: 12V jump box (which I will probably replace the cables with, IDK though, cables are quite compact...) and a set of the little orange disks with the LED's in them that act as warning triangles/flares.