You don't need a DVD system of handheld electronic games, 
http://www.momsminivan.com/  is a good source of ideas and games to make family road trips more fun.
 
Outfit the car/van for kids: Buy some car organizers to fit over the center console  or the seat backs. Children can store the toys, books, balls, crafts, pencils and paper supplies in there. 
 
Encourage children to make a travel scrap books. While travelling they can make notes and draw pictures.  Bring along a disposable camera for them to take pictures.
 
Children needs a break every two hours in a rest area or park. Let them run around for 10 minutes or so.  If it is a long trip, bring a change of clothes.
 
Have some snacks (which are nourishing and easy to clean): dried fruits, nuts, cereal - single serving packages and crackers.  Don't forget non-spill cups and paper towels.
 
Have playtime with lunch - sandwiches in a park or eat in a family/child friendly restaurant.
 
Carry some small blankets and pillows in the vehicle so naps will be more comfortable and restful.