But what about snacks?
How many times have you regretted eating that king-sized candy bar, or a day-old, shriveled up hotdog at the gas station because your mouth was a little bored? Or perhaps YOU have the will power to purchase a questionable looking apple, but your kids are whining for snacks that will rocket them into hyperspace (only to send them crashing down into a sugar coma a few minutes later.)
If you pack a snack box in advance, you can avoid wandering the gas station for goodies. Instead of Moon Pies and Pecan Logs from Stuckey's (those who have been through the South will get these referrences) you can have at your fingertips things that are good for sustained energy: water, Gaterade, nuts, fresh fruit, whole grain crackers, cheese, granola/granola bars, healthier versions of trail mix, etc.
I also like to pack a thermos of coffee with the perfect amount of milk, rather than settling for old coffee with those creamers that have a half-life of 3 kazillion years. Granted, 10 hours into a trip I might drink anything resembling coffee, but will avoid the powdered machines if at all possible.
My friend Jeff and I took a road to trip a couple of years ago - while listening to NPR and a few CDs from each of our collections, we shared various sandwiches, grapes, clementines and of course, a little bit of chocolate. There were no internal discomforts that often accompany eating on the road, and we saved a little time as well. It was great!
If you absolutely MUST pack junk food, at least you've saved a little money by buying it ahead of time.