Fun In The Car - Goody Bags
As our kids get older, they travel much easier, they don't get so antsy and can travel 8 hours without too many squawks.
When they were younger I'd make up goody bags - little ziplock baggies with specials in them - a piece of gum, 2 Starbursts, some trail mix, some M&M's, etc.
Every 1/2 hour (this was when we'd go 4 hours max a day) they each had their turn reaching in a bag and seeing what baggie they pulled out.
A treat for traveling well!