Saw this on reddit
Additions?
Towel, mags, more mags, ammo, surefire, batteries. He hit on gloves, I like to have some in the cabin too. Even if they're just $1 cheapies. Also a real tire iron/4way, and good jumper cables.
Winter time I add relevant stuff, blankets, a scarf etc. Each of my kids has a blanket in the car just for their use.
I personally found that the advice given in the link of the original post to be lacking, so I fixed it. I've broken it down the most logical way I could think of, and remember not everyone will need everything. This post will require a little bit of common sense, for example if your rarely travel outside an urban area, you probably won't need to bother with the Emergency Kit; however someone who frequently travels remote rural areas or the back country would most likely be better off keeping one in the trunk. Also, as far as the Tool and First Aid Kits go, these are just examples of basic contents. You can certainly add more items to it, but in general, I probably wouldn't take anything away. Keep in mind also that, unless you truly are the Forever Alone Guy, you will need to consider passengers and any unique needs they may have. For example if your wife/girlfriend whoever is has allergies, it wouldn't hurt to throw in some benadrly or even an epi-pen if it's severe.
BASIC TOOL KIT
I doesn't have to be anything major or expensive. All you need is a sturdy container with the following contents inside:
Socket set/ratchet, flat head screw drivers: 3/16, ¼ and 5/16, Philips size #1 and #2, pair of regular slip joint pliers and a pair of needle-nose and locking pliers, adjustable crescent wrench, wire cutters/stripper, hammer, an assortment of extra fuses, heavy duty jumper cables, gloves, a couple of shop towels and I usually have a roll of electrical tape in there as well.
BASIC FIRST AID KIT
Again, it doesn't have to be a giant, store-bought monstrosity. I would personally suggest getting a small Pelican type case that is crush proof and water tight and filling it with your own supplies. If you're a father/husband/good guy and you make multiple kits it's easier and cheaper than buying what is typically an overpriced and poor quality store bought kit. If you live/travel out in BFE and utilize an Emergency Kit, I'd make sure the First Aid Kit is small enough to toss in it without too much trouble. Anyway at a minimum, I would include:
Bandages (assorted Band-Aid type), gauze, gauze pads, antibiotic ointment, scissors, first aid tape, tweezers, alcohol swabs, elastic bandage, instant cold pack, pain relievers and burn ointment.
Here is a particularly good opportunity to show your good judgement, foresight and common sense. For example, my son suffers from bad acid reflux, so I would include some antacid. If you're trained in emergency medical or whatever, by all means add more stuff to utilize your abilities. Maybe you're ok but someone else needs help, be a Good Guy.
Emergency Kit
Not everyone will need this. This is mostly for people to take long trips or those who live out in the middle of nowhere. Again, this is just a basic idea, take it and expand it to fit your area and needs. I would put the following items in a Camelbak type bag, that way you have a convenient way to carry the items and water.
550 Cord, duck tape, space blanket, food stuffs, poncho, signaling mirror/whistle, fire starting Material, signaling flares, signaling panel (VS17), dry socks and sturdy footwear, good fixed blade knife.
In the Trunk/Cargo Area
Put whatever kits above you use and the following: A real jack, lug wrench/tire iron, a quart of oil, a gallon of antifreeze/coolant, folding shovel, can of Fix-a-Flat, empty fuel can, large water container-full of fresh water (for drinking-fill your Camelbak with it if you use it).
In the Center Console/Glovebox
This items you will want to be able to reach from the driver's seat:
Emergency Egress Tool, a bright, compact flashlight, map. Also, a bottle of Acqua Di Gio (or at least a thing of Axe) and a pack of gum, because this post isn't about survival as it about what Men should have in their vehicle.
On a similar note, fellas, don't be that guy that comes into work the next day smelling like lavender and coconut and wearing the same thing you wore the day before. You know what I'm talking about: You end up at an impromptu stay over and end up showering with whatever girly crap she has in her shower and wearing the same thing to work you wore the day before because you didn't have time to return to the Bat Cave before work. I recommend -at least- having an extra shave kit with an extra toothbrush/toothpaste, razor/gel, deo and whatever Manly Soap you use. Putting this in a gym bag with an extra set of clean whatever-you-wear-to-work would be ideal.
Finally, I didn't include stupid stuff that everyone already has in their vehicle like a car charger for their phones and whatnot. I hope this is more helpful than the original version posted earlier. I would also like to say I did not make this to be a dick, I just thought it wasn't very helpful and wanted to improve on the idea.
Additions?
Towel, mags, more mags, ammo, surefire, batteries. He hit on gloves, I like to have some in the cabin too. Even if they're just $1 cheapies. Also a real tire iron/4way, and good jumper cables.
Winter time I add relevant stuff, blankets, a scarf etc. Each of my kids has a blanket in the car just for their use.