The list of items you should keep in your adventure car is probably very similar to the list of things your driver’s education teacher or worried parent told you to keep in your car — except when you need some of that stuff, you might be miles from cell phone service, or on a rough road that will take a tow truck half a day (or an entire day) to drive down to pull you out. So I focus on two things: self-rescue, or getting myself out of a “stuck” situation, and self-care, to stay alive when self-rescue is impossible and I have to wait for help.
A friend. Friends are great for lots of things, including conversation while hiking, but in a sketchy driving situation, they can help immensely: pushing your car out of a snowbank, directing you from outside the car as you try to maneuver over a rock or other obstacle and helping you turn around in tight situations.
Bicycle tire pump or air compressor. On sandy roads, it can often be helpful to deflate your tires to increase their surface area and thus increase your traction — but you have to inflate them again. If you have the money and space, an air compressor works best, but a bicycle tire pump will work in a pinch, provided you don’t mind using a little elbow grease.
Rubber floor mats. Many a stuck-car situation can be solved by tossing an upside-down floor mat under a tire to give it just enough traction to get out of any slick spot.
Tow straps. If you have your own tow straps, you don’t need another car with tow straps to pull you out of a bad spot — you just need another car.
Jumper cables. A dead battery is easier to jump if you always have jumper cables with you.
Shovel. If you don’t love digging a stuck car out of the snow with your bare hands, a collapsible backcountry skiing shovel fits in your trunk and is a lot more efficient at moving snow.
Kitty litter or sand. If you’re spinning out on ice or snow, a few handfuls of kitty litter or sand can give you just enough bite to get moving again.
And if you are hopelessly stuck and waiting for help, these self-care items can make your time a little more comfortable. Lots of them double as car-camping gear, so if you’ve got them in your car already, that’s a handful of things you don’t have to pack next time you head out for a night under the stars. And of course, some of them double as self-rescue/car repair items.
Headlamp. Flashlights are great, but if you want to use both hands to do something, a headlamp is way better.
Gallon of water. You can drink it while you’re waiting for help to arrive, you can use it to fill your radiator in an emergency, and you can use it to fill water bottles if you ever get to the trailhead and realize you don’t have quite enough water for your hike or ride.
Multitool. Sure, you have a whole chest of tools at home, but you’d be surprised what you can do with a multitool that has a knife, pliers, and a couple screwdrivers.
Duct tape. Because duct tape.
Sleeping bag. If you’re stuck somewhere overnight, you probably don’t have enough gas to keep your engine running all night to keep the heater on—but you can get into a sleeping bag and stay warm when the temperature drops.
Food. You’re probably not going to starve to death if you get stuck somewhere, but it’s nice to have some calories handy to keep morale up.