The World Rally Championship takes place on public roads. The rally cars, which compete on various types of roads, such as tarmac, gravel roads, snow-covered roads, are maintained by rally mechanics. During 3 days of intense rally, the pilots have to drive as fast as they can on 5 to 9 time attack sections a day which can be brutal on their machines. For this reason, maintenance is an essential point. As soon as time attack is over, the driver indicates to the team mechanics with his radio what has to be fixed and what settings have to be changed. After the car has entered the service park, the mechanics have to work as fast as they can. For example, they will need to change a transmission in only 20 minutes. A victory is not only due to drivers but also to effective mechanics.