I bought it to use not to clean. :) :)
In the spring I wash it with soap an water followed by a wash and wax. We usually do the interior also.
It usually does not get put away until November sometime January. I used to clean it at the end of the season but it sits in the pine trees all winter and needs to be cleaned in the spring regardless; especially if the mice have decided to stop in for a visit.
I must admit I have not seen any better gas mileage, cheaper gas prices or better camping rates because it was bright and shiny. :)