For the 19 hour car drive to Otakon, we played the license plate game. I think we ended up only missing one state and had 4 Canadian provinces (?). We also played name my friend's future child's name with some of the goofy town names we came across.
I think it just really depends on how well you get along with the people you're traveling with. I enjoyed my group so much that the books and video games I would bring didn't get touched much despite the long drive.
Currently working on:
Nene (Bubblegum Crisis)