What do you keep in your car?

Wrangler or MX-5? Cause the kit is wildly different lol

This might not be the intention of the question, but DASHCAM. If you don’t already have one, get one.

There’s so many good reasons to have one. DON’T get the cheapest $30 one you can find on eBay. It’s a safety device, so go with one that has video reviews and has been around for at least a few years.

Make sure it mentions using a super capacitor instead of a traditional battery. Batteries will swell and quickly lose life and even potentially kill the camera in the heat.

Get something at least 2K resolution to be able to read license plates at a reasonable distance and test it regularly. I’ve had a previous camera show that all that good and recording only to discover half the footage was being corrupted.

If your car allows for it, get one that has a built-in rear camera loop for rear-end accidents as well.

Here’s the brand I’ve been using for a couple years and have had excellent results: https://www.viofo.com/

This.
I had someone merge lanes into me. I sensed it, evaded them, and drove up onto the curb. Wound up with a couple thousand dollars in damage - new tire, wheel, rim, control arm, and strut.
Without video footage of the incident, I would have had to rely on my insurance company taking my word for it.
Catalyst for the purchase was many years earlier where I was hit by a drunk driver at 2AM while making a left turn at an intersection, it was raining and they did not have their headlights on, they had two friends with them and I was alone.
Insurance ruled that, based on the point of impact, I was at fault.
I tried to get into dashcams for a few years but even the expensive brands seemed to be absolute garbage. After dealing with terrible apps, poor UI and batteries refusing to charge after being shelved for just a few weeks I simply gave up.
If I got back into it I would probably end up building my own with a Raspberry Pi camera.
- The advertised brands like Garmin are definitely garbage and I can attest that they almost all use normal batteries. You have to go with a source company (like the one I provided) that actually specializes in them rather than a brand reseller.
Are recordings password protected?
- Not on this one. The SD card is quick to access right on the side of the unit and isn’t encrypted. I never use the WiFi features, but since the supercap only has a few seconds of battery life and you’ll be a moving target for the WiFi signal, I can’t imagine there’d be too many people clever enough to steal things off it.
  You could easily pop out the SD card every time you left the car.
- There are dash cam systems that support encryption, and other cool features like two mirror copies made at the same time... but not the retail systems, the commercial fleet mdvr systems, they tend to be bulkier, and more expensive (like 1-2k USD)

In my glovebox:

Driving gloves (lol)
Tyre pressure gauge (I don't have TPMS)
Service booklet

In the cabin:

Dashcam
Phone holder
Sunglasses

In the boot:

Jumper cable
Space-saver wheel
10" 250W subwoofer, 4 channel amplifier, and 6x9 speakers

Eehhhh .....

water/packets of juice
swiss army knife
rope
tow cable
jumper cables
tie-wraps
velcro
tape
wd40
2 mugs
binoculars
candles+matches
couple of plastic bags
dog treats
blanket
rainjacket
winter jacket
scarf & beany
toolkit
toiletpaper
solar rechargable flashlight
mini compressor
straps
penci & paper
axe
medical kit
spare bulbs of all kind
assorted spare fuses
.....and all the rest I forgot to mention

(No, i don't drive around in a box-truck ;) )

Should be obvious but you should have tire repair stuff in your car. Especially since no one includes a spare tire kit anymore.

I got a tiny Harbor Freight air pump I keep in my car. It saved my ass on my last road trip when I ended up in the middle of absolutely nowhere with a tire pressure warning on. Stopped every couple of hours to air it back up until I got to the nearest Discount Tire on my journey. I also keep a tire plug kit!

I have to chime in with a “Discount Tire kicks ass.”
Also it’s known as America’s Tire in California (the Discount Tire name was already taken when they arrived to the California market).
- I was about to rage before I remembered my beef is with tires+. Every time I tried to take something in there, they would say "it's illegal to..." No it isn't, you're just trying to upsell me.
- Yeah they've been taking good care of me and my family for years.

Dashcam was a damned good suggestion. I'll add first aid kit, blankets (if you get cold weather), and signal devices like road flares, reflective signage or small traffic cones. Maybe a few bottles of water and calorie-dense snacks. Just remember to consume and replace them periodically.

I keep a bunch of tools on hand because of work but tools are usually one of those things you accumulate over time as they become needed. A good start would be a socket set and a bit driver. Maybe add a breaker bar and a "stubby" driver or 1/4" ratchet for tight places. 1/4" "security bit" sets usually have some flatheads, PH1-3, plus a range of hex and torx bits with the little dimple because "security." A bit driver handled all the fasteners when I replaced my tailgate handle and my interior passenger door handle.

A tow rope and jumper cables are both things that others can use to help you should they not have their own. I know I like it when the person I'm jumping has their own cables ready. My own are usually buried in the compartment under my rear bench, which itself is often buried under toolbags and such. I also keep a couple square-ish off cuts of 2x6 in the bed which make good platforms for a jack/jack stands. You don't usually get to pick where or when you're forced to change a tire and jacks tend to sink and lean in soft earth without any support to spread the weight.

EDIT It's a real late edit but I still don't see it mentioned and it reminded me of something else too.

Thing the first: Fire extinguisher.

Thing the second: Some sort of mounting bracket it for it. Some will attach to a pillar, others might be made to reuse the bolts at the front of your seat mount. Wherever your fire extinguisher goes, it needs to be secured. Same goes for tools and other items which could become projectiles in the event of a collision.

It's a work truck so quite a bit. Full set of tools, including powertools, hardware and some lumber.

However, to actually answer your question: blanket, some warm clothes, hi-vis vest, 5 litres of diesel, common hand tools, socket set, flashlight, charging cables, baby wipes, a hatchet and a tow and recovery rope.

Change of clothes
Blanket
Jump Box
Phone charger
Sunglasses

I have sometime similar to this setup myself.