While you're taking a road trip, your kids are a captive audience. Take the opportunity while you have their attention to challenge them to think positively by playing Fortunately-Unfortunately. In this game, one person will make an unfortunate statement, and then another player will counter the statement with a positive response.
Fortunately-Unfortunately presents endless possibilities for creativity and positive thinking. For example, one player could make the statement, "Unfortunately, a lion is going to attack us." A second player would counter with a more fortunate statement such as "Fortunately, I took lion taming lessons." The more exaggerated and silly the statements are the better!