Driver drives. Crazy person in the pass seat tells the driver where to go.
Click
HERE for an in car vid. The voice you hear is the co-driver reading off the pace notes. What are pace notes? Think Garmin with a TON more detail. Tells the driver which way the road goes, whether or not to cut a corner, how fast to go, if there is a jump or not, and so on.
By the way, (IMO) I picked a vid from one of the greatest rally drivers ever-Mr Colin McCrae.