They are also probably clean and shiny because they are million dollar racecars with equally large contracts that most likely have a stipulation that says that the cars are to be clean and shiny when they race in order to best represent the team. Also, Wax will make an incredibly non-noticeable difference on an F1 car. They accelerate, decelerate, turn, and everything else so often that a very slight decrease in wind resistance will make no difference. Also, with all the wings and splitters that they have to create downforce, there will be so much resistance caused that simply making the paint smoother won't do a thing.
Now on land speed record vehicles like at Bonneville, it is believed to make a difference and has been a common method for many, many years.
