Rally Race question
 

Sometimes I watch Rally Racing on the Speed Channel. I was just wondering what it is that the guy in the passenger seat is reading to the driver. He reads all the time, even when they are going down a straight stretch of road. Can anyone tell me more about what is going on?

Thanks

usually the navigator (or co-pilot) speaks of the road condition, the upcoming turns (usually one turn ahead of the currently approaching turn), sugguested speed/gearing... and more.