Make sure you have water in the radiator and wiper fluid as well. If you don't already have one in your trunk, you should put together an emergency road kit. Nothing is worse than getting stuck in the middle of nowhere without a spare tire, jack, and or a pair of jumper cables. Make sure you bring a flashlight with extra batteries. If you do break down and get stuck on a cold night waiting by the side of the road, you'll be glad it's there.
Companions are key.
If you're going to be stuck in a car with someone for several hours it better be someone you like, or are can at least tolerant of.tolerate. Juice boxes, granola bars and other snacks and fruit are also good to have on hand to keep them happy. Check out our Travel Toys article for more information. Remember that lots of main roads have tolls. There's nothing worse than holding up a line at a tollbooth while you're digging in between the seats hoping to come across a sticky quarter or dime.