Food supplies in a bug-out vehicle include hundreds of pounds of wheat, rice, and beans, and enough honey, powdered milk, canned goods, bottled fruit, vitamins, dehydrated fruits and vegetables, salt, pepper, spices, and oil for several months. In addition, the kits often contain high-calorie energy bars, a cooking kit, utensils, liquid soap, and towels. The water supplies may include bottled water, filtering kit, bottles, collapsible water containers, and chlorine bleach for water purification. Food preparation and washing equipment may include items such as a grain grinder, a bread mixer, a strainer, a manual can opener, a steam canner with canning jars and O-rings, cutlery, knives, an electric 12-volt cooler icebox, kerosene lamps and heaters, kerosene or propane stoves, extra fuel, a clothes wringer, a foot-operated treadle sewing machine, and an electric hot plate (which would require an inverter to operate off a car battery).
However, if some tales of survivalist stockpiling are to be believed, our nutty neighbors have enough of the social lubricant squirreled away to hold the most epic end-of-the-world-party of all time outside of Edgar Wright's social circle. It might not be practical, but who needs practical when you and everyone you know is doomed to die from radiation poisoning or cancer?
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!