Algreary,
Our kids (now 4 and 5 yo) are amazing with travelling in the car. Yesterday we did a 5 hr trip to get away for Easter, no stops.
One of our biggest 'tools' is iPod's with kids headphones, and kids music. They will listen to it for hours, and can even send them to sleep at times.
You can fill it with a bunch of kids artist, worth the investment. Also got some audio versions of kids shows, ( ie Fireman Sam)
Eating is another past time of the kids when travelling, can't seem to fill them up!!!!
Also a mega-sketch...
They use to use this electronic ABC game that let them draw along, guess letters, etc (I can still hear the music playing!!!)
Even toy cars get a run.
But it's all about the music....
Good luck, hope some of that helps