What does a rally co-driver do exactly?

Well, after traveling through the stage at slow speed the co-driver reads the notes back to ensure the driver has the details they need to drive as fast as possible through the stage the following day.

This video shows how accurate both the notes and the note calling must be. To spice it up, imagine the video at three times the speed and some crests as jumps and then you will get an idea of what it is like to be in a rally team!