This will depend on the kind of tools you have handy and the kind of atmosphere you are looking to engender in your vehicle. Thankfully, there are plenty of games that can be played with just the mind alone (and a willing attitude of course). One of the more creative road trip games involves finding license plates and then replacing each of the letters with other words to create humorous or thought-provoking statements. The winner is chosen by the person who chose the license plate initially, though there does not have to be a winner for this to be fun and engaging.