Emergency Kit

Oh, also I carry an old, used accessory belt that is in fair condition, in case mine were to break I could get home without worrying about depleting the battery. Also a fair condition windshield wiper blade in case one totally shreds itself for some reason. Ice scraper if you live in North-ish like me.

Also also, hose clamps and duct tape and zip ties. And a set of automotive fuses. No idea when you're going to have to either replace a blown fuse that went out randomly to limp the car home, or reattach a hose somewhere that has come loose, or repair a leak in a hose or line, or reattach your bumper or body trim to your car, there's a whole host of problems that having a couple fasteners on board solves.

First aid kit, Swiss army knife with as many functions as you feel comfortable with, bottle of water (replace that every once in a while), warm blanket, towel and maybe an old cellphone with a battery that is charged when you need it. Don't carry a bag of tools with you at all times...

Why do you shill for compressors? Are you afraid to operate a foot pump?

Also, you don't need half a ton of 'emergency' kit if you /maintain your vehicle in working condition/.