I love Gummi Lifesavers on road trips. They're good, poppable, and don't melt. We also grab donut holes, which is nowhere near healthy, but hey, if I can entice the kids to behave with a donut hole, then I'm okay with it! We do bring veggies and some easy fruits--apples, usually--in the car.
The first few times we traveled from home to my parents--a 12.5 to 13 hour car trip done in one day--we stopped for lunch. But that makes the day even longer, esp. the time we arrived about 5 min after TWO coach buses filled with Boy Scouts arrived. We waited forever to order and then the food was even more crappy than I expected toll plaza food to be. Sigh. So now we pack PB sammies and drinks along with our typical cut carrots and (maybe) bananas. (I don't like having bananas in the car: while I love them, their smell seems to linger. I don't need to smell them for 12 hours, ykwim?) Dinner is usually snack-type food, but we try to make it semi-healthy to make up for the donut holes lol.