Not sure about only for "possibles" BUT,
with cell phone batteries pretty cheap to buy online to replace a battery that runs down fairly quickly, maybe one should consider keeping a few extra batteries charged up and stick them in your car.
I keep two in my own glove box. This way I always have a fully charged battery in case the car breaks down and the battery is bad.
Speaking of which, they make something called an emergency battery pack that will provide electric current in great abundance to JUMP your car and still have plenty left over to plug other things into.
Put FOOD ITEMS that last in your car as well as a case of bottled water. When I say food items, i am talking about things like Granola Bars, Protein Bars (which I always carry when driving), a can of Trail Mix. This way ya gots nourishment when ya is stuck and going nowhere.... and water too.. or Gatorade...