Smart alec! 
We also tend to take a container of gorp with us as well, just for the variety. So to be precise, our usual trip snacks are: bag of home-made Chex Mix, bottled water, bag of gorp. The gorp recipe varies depending on the season and the temperature.
Peanut butter sandwiches-refrigeration not necessary, and the stuffing doesn’t come out the back when you eat it either. Non-juicy fruit (ever try to steer and lick peach juice off your forearm? Fun, but dangerous.)
You shouldn’t be eating anything when you are driving. It’s distracting and not healthy anyways. Stop every few hours to stretch out and just eat a proper meal on one of the stops. Bring a sandwich or something.
Jelly beans. Fat-free and tasty.
Not really food related, but remember to use sunscreen. Even in the car, you can get sun damage.
Robin
Fondue. Just make sure the flaming sterno is snuggled down into the passenger seat so that when you stop fast and cooking oil sloshes everywhere that it doesn’t erupt into a fireball. Your moonroof can double as both a chimney and a way to cool the scalding meat skewers when they’re fresh off the fire. Eh, on second thought…
No matter what you’re bringing, it’s nice to include a couple of apples to munch on afterwards. A place to brush your teeth isn’t always available and a nice, crunchy apple can give you a pleasant case of freshmouth for the remainder of your trip.
Wow, lieu, I wanna travel with you!
Have none of you people heard of dark chocolate covered coffee beans?
As my father said, potty breaks are for pansies. You only stop when the car needs gas…that’s once every 400 to 500 miles. No sense drinking all that water or tea or other liquid. You’ll just have to stop ever hour to let it out. Caffeine in it’s raw form, the ultimate road food.
Take nothing- a good chunk of the fun of a long roadtrip is the food you can get along the way.
Go to the snack aisle at Target. They have some great combinations there.
My favorite is a fruit and nuts (sorry, can’t remember the exact name) combination that has dried banana chips, dried apricots, crystalized mango and papaia, dates, raisins, dried cranberries and almonds. You can also buy a lot of different dried fruits by themselves.
Others have mentioned beef jerky. The less dry stuff is usually better in the car (doesn’t make you as thirsty). Turkey jerky is good too.
Kalhoun mentioned grapes. Always good. Conveniently bite sized!