If travelling a long way by car, split your journey up by stopping at a motel overnight. On the journey, give them to the kids to open. Give the kids some colored pipe cleaners for bending into different creations. Take a gamboy, or other hand-held game. Everybody gets a pencil and paper.
Players write as many words as possible that start with that letter.
Whoever has the most legitimate words wins. Decide in advance whether you can finish writing a word you've already started when the game ends. Now, give yourself one more minute to write a sentence with as many of the words as you can. Car game - Invent stories about people in the car next to yours. Get into lots of details, such as whether they snore loudly or are afraid of spiders.