Autonomous cars will certainly go to the Model of 100% car-sharing as a service 'universal taxi ". Each trip, we will have a different and suitable vehicle (no need fr a Break to just go to at 2 an evening with friends) used by an unknown before us, and after another unknown. So there will be a possible trend towards the car sanitized and impersonal ...
Why not give a little touch of magic with in every car, a "surprise box"? In this box, my predecessor will leave a book or CD (if it still exists) or a DVD or an album title or an exhibition or a board game he loved and he wants to share .
If his proposal appeals to me, I take the surprise and file a surpise in return for my successor. If my curiosity has been piqued, I let his surprise in the box, may be that my successor will find it friendly.
Of course, I leave a small sheet or a word accompanying the book, which will be supplemented in turn by the person who takes my surprise and share it a little later again.
This is simply extending the principle of bookcrossing to autonomous cars (which are used to read when moving!) , to bring an unexpected moment in our travels.