Here's a radio ad created for Gandhi Bookstores from Mexico City that you can actually read:
In congested Mexico City, people spend hours sitting in traffic. Using RDS systems that is used to identify stations and artist and tracks played, they transmitted a short message on commuters car radios.
Announcer: If you are stuck in traffic look at your stereo's screen.
Screen: This advert promotes reading. That's why you are reading it.
Announcer: Gandhi Bookstores. Keep reading.