This depends on personal preference and also who will be riding in your car most frequently. If you're a minimalist at heart, you might stick to a couple of charging cables, hand sanitizer, tissues, wipes and emergency supplies you deem necessary. If you want to be prepared for anything and everything, consider purchasing several car organizers to store your things and maybe add in some blankets and towels. If you're traveling with kids, you might want to bring along some crafts, fun car games and snacks to ensure they are entertained and have a full stomach.