One can have gear and still be neat and tidy and clutter free, its all in how you keep it.
I'd start with one of those small first aid kits designed for a glovebox.
Add in a flashlight with batteries removed and a pack of fresh batteries to go in it.
One of those Window breaker/seat belt cutter tools.
Spare battery for the keyless entry remote.
Gloves, a nice looking pair in the glovebox to use when scraping ice, a pair of work gloves with the jack and lug wrench.
A roll of shipping tape and clear plastic sheet (a pre-packaged clear shower curtain works well) to cover a broken window.

Be careful about putting things in someones vehicle without their knowledge. Many government facilities do random searches. You would be surprised by the things banned on most of the military bases on which I have served. "but I am just coming to watch the air show" won't be accepted as an excuse.

Your vehicle will be thoroughly searched, the many hidden spaces in the body will be opened and all your possessions dumped on the ground. You will then have the opportunity to put your vehicle back together.

Things like fire starters, propane tanks (the one pound tanks for small stoves make a dandy explosive), knives, axes and many other common survival stuff will probably be confiscated.

I was amazed at the hiding places they showed me in my vehicle. Took about 2 hours to put it all back together. I had left a pistol magazine (empty) in a small box that somehow got under the rear seat.

Nomad....been there, done that...

Phew, I hadn't thought of that. Sensitive areas and border crossings come to mind.

So maybe if you can't take it on a commercial flight with your carry on, it's problematic. Hmm!

"Hiding something usefull in someones car"-idea I find utterly stupid. If caught in an accident or other dire situation I would not think of searching my car for something if I have not put it there myself.
So please help someone but tell them about it.

Keep thinking if mindlessly contained something that could be seen as elicit. Like white powders or pills. An uncomfortable conversation will ensue if get stopped.

I certainly wouldn't "equip" someone else's car. I'll equip mine, and advise them on how to equip theirs if they ask. But it's not my place to hide stuff in their car that they would never find in the first place.

I guess this thread makes me appreciate my wife's truck a little more. I call it "The RCP" (she hates that!) "Rolling Crap Pile". But whatever you need - be that gardening tools, plumbing repair items, a bazillion half-consumed bottles of water, or a Sawzall ... you can bet it's probably in there somewhere.

There seems to be no logic in giving someone stuff that they do not want or know how to use. When I gave my kids a few multitools I explained the logic and uses.

I told them to put the multitool in the center console (not the toolbox in the trunk). They should be able to reach the MT while they are in the driver seat. If any of them was in an accident and needed a knife to cut the seatbelt, they can use the knife in the multitool. Or even it can be raining outside the car, or some stray dogs were nearby when I needed a pair of pliers a few years back.

Regarding clutter / declutter.
My car trunk is a dump box. You can find shopping bags, coat hangers, nylon rope, old (spare) shoes, beside the toolbox and cane (in case my knee problem intensifies ). Also there is a "kitchen" bag ( which can help me if I had to eat something, it includes spoon & fork , steel cup, tissue paper ..etc.) So, yes, I am in the clutter camp regarding the trunk, but the seats are reasonably clean and tidy.

With that in mind, I don't have a "survival kit" per se. Stuff is scattered. Fixed knife is in the toolbox with other tools, Fleece blanket is free on its own, Spare socks and other smaller items are gathered in a small old bag, first aid kit is in the glove compartment. And so on. This seems more practical as I needed and used first aid kit a few times but socks were never needed in many years

Regarding gifts for other people. IMHO, giving them something they do not value or need is waste of money and energy.

I have given people things in the past (general stuff, not related to prepping) and in many cases when I visited them again I noticed that stuff tossed here and there. One time I liked a book so much I ordered two copies and gave one to a very dear friend. He laughed and said: who needs books these days? If you need to learn anything just Google it!! Now I only order a single copy for myself.

So, giving people hand to hand will show you if they need or want that stuff.

I see the wisdom in your argument. Adding items without their knowledge would have little use. Helping them add items in places that are out of sight would be more effective.

It's not like a commercial vehicle where certain safety equipment can be mandated (first aid kit, fire extinguisher).

It's a recurring frustration to me when I read stories of people stranded in blizzards without anything to help themselves. The solution still eludes me.

Yes, when I bought my car it had a fire extinguisher and first aid kit.
I moved the FAK to the glove box where I can reach it from my seat

Regarding people, many or most are complacent and may be upset if you shove things into their cars. The only scenario where it will be great news is when someone is stuck in a blizzard and call you , then you give them the surprise that you have hidden a survival kit in their trunk. But most likely scenario is that they find it in the trunk and be upset about you being so intrusive in their lives.

Sad, but this is how life goes.

Last month I gave one of the kids a few tools, and they still sit there collecting dust. He never thought of putting them in his car or even his desk drawer. If he has a problem one day, I don't know what he will do, but most likely he would use his smart phone to call a technician or something.