Best intended for long, multi-state trips, make a list of the 50 states for each participating member in the car, and they each check off the state when they see a car with that state’s license plate.
This can be entertaining for kids as well as adults and it can also be cooperative or competitive. An added challenge is not allowing checkoffs for the state you’re currently in. The game exercises one’s observational skills as well as teaching what each state’s license plate design looks like and can also be played simultaneously while conversing or listening to music, allowing it to last for hours.
For a twist, create individual BINGO cards for each player with various states listed.