We are driving with a 8, 6 and 2 yr. old. I am making them road trip kits. I have trays that I made with a little cushion and dollar store cookie trays attached. I made all kinds of magnetized games/puzzles. I also did road trip bingo, battleship, yahtzee, tic-tac-toe, hangman and a baseball game I found online and laminated them. This way they can play the games over and over. I found a tutorial on pinterest on making I spy kits. Go to the dollar store you will find tons of puzzles and little craft kits to bring with. Also they had some magnetized tangrams there that I bought for the kids. Oh and I bought mickey alphabet, number and color flash cards from the dollar store and punched holes in them and put them on a book ring.
I also am putting together reading and movie kits. I am doing all kinds of Disney books in a kit for each of them at their level from the library(will just make sure they don't leave the car) and am checking out movies to watch in the car. Plus lots of Disney themed snacks!!
Here are a few of the links I used.
http://laura-elephantjuice.blogspot.com/2008/12/handmade-holiday_16.html
http://mykindofmakeover.blogspot.com/2011/07/magnetic-puzzles.html
https://www.earlymoments.com/Fun-Activities/Disney-Fun-Activities1/
tray...mine has just the lap cushion, but I added a magnetic crayon holder made out of pringle containers cut down
http://prudentbaby.com/2012/08/baby-kid/diy-travel-lap-tray/
Here is on from the DIS
http://www.disboards.com/showthread.php?t=226819