Some of us keep absolutely nothing in our car trunks, while others have enough packed to live in their cars for weeks. Somewhere in between is this list of things we think every car owner should always have on hand.
I never carry a fire-extinguisher. Putting out a fire under your hood is difficult and dangerous and I wouldn’t recommend it to anyone. Unless it was tiny fire inside the cabin that I could put out with my shirt or shoe. I would always get well clear of any burning vehicle and simply let it burn. Let the insurance company or the fire department sort this out. If you must carry a fire-extinguisher by law, or just feel safer with one, then the sensible place for it is by your driver’s seat, not buried in the trunk of your car. Make sure you know exactly how it comes away from the mounting bracket and how it works because seconds are vital when putting out a fire and you don’t have time to read the instructions.
I also never carry spare gasoline as it is very dangerous stuff to carry around in the trunk of a car (never under any circumstances carry it in the passenger compartment). Read your car’s manual and make sure you know how many miles you can drive with the empty light on before the car runs out of fuel. Usually you can do a good 30 miles on the light sometimes more. Good driving means you should be checking the dials on your dashboard regularly while you drive and filling up whenever you go below ¼ on the tank. If you just cannot get into the habit of filling up, or you pass by gas stations hoping the next station will be a 10 cents a gallon cheaper, then the gas-o-haul disposable fuel tank is a good, safe, space saving option. But carry it empty and only fill it up when you need it.