Also, a pair of regular pliers, a pair of needle nose pliers, a crescent wrench ( 6 inch will do most cases), a good quality flathead screwdriver and a Phillips head screwdriver ( by good I mean, not the real cheap Tiawan ones, that bend or break. Get Stanley tools, Craftsman or Benchtop). Maybe a pair of Visegrips.
Sometimes you can buy a tool box with most of all this within it, and then just add what you want extra.
Add some black electrical tape, a good flashlight, some sort of reflectors perhaps (to put along the roadside if stranded) Jumper cables might get your car restarted if a passerby helps you.
And use your own judgment on what to have with you, depending on the weather. I carry an extra blanket and an old parka in a plastic bag. Might not need either one, but in having to walk in cold weather, the extra parka comes in handy. I found that out, in a snowy dark night, about 20 below zero. I had my extra parka, and it helped keep me warm, while I was trying to get help. These large plastic bags that Comforters come in, are great for storage of such items, including a pair of gloves and cap with earmuffs.
The idea is to be able to get your car restarted if you can, and so these tools can fix almost anything, with some exception, of course. If you cannot fix it, you will need to be able to keep warm and safe. Use your mind for that.
Cell Phone.
Flash-lights, pliers, screw drivers, electric tape, Lighters and stuff. I suggest you make a complete tool box and keep it in your car all the time since it would even save a lot of space for you. You can even look for a ready made emergency car kit online such as on websites like american family safety, Life secure and http://www.emergencybugoutbags.net/. This will save you time and won't even cost you much.
Add in a gun, ammunition, pocket knife, cigarette lighter, those easy-start fire logs, some water, $20 cash, and a state ID.
What do you expect to be able to fix in a stranded car. A flashlight and a tire gauge should do it. If you maintain your car and change your battery at the first failure even battery cables aren't necessary. I am old and have not used them on my cars in decades. Now the rest of the population that doesn't maintain their cars. That is what they wind up getting used for. The most important thing is your phone and AAA membership. And a towing outfit number. That is it. I would not even recommend changing a flat tire your self unless you can pull off the road very far. Too many get run over doing this.
LED flashlight, channel lock pliers, metric combination wrench set, digital volt/ohm meter, jumper cables, mechanics wire, duct tape, Phillips and flat screwdriver. electrical tape. three foot piece of electrical wire with alligator clip on each end. This will give you a good start. Harbor Freight is a good supply source. All items listed can be found there for less than $50.00.
Reflectors, 6V lantern battery flashlight, small ABC fire extinguisher, a cheap socket/screw driver set, etc.
In cold winter weather add - jumper cables, emergency blanket, sand/cat litter, emergency food and so on.
On long trips I always carry extra oil, PS-Trans fluid and a old antifreeze bottle full of water with a gas can.
I am in the process of putting together car emergency kits and have no idea what tools to put in there. I know all of the survival/emergency stuff but have no idea what tools I should keep on hand.