I think you can wash a car too often and cause long term damage. Years ago the shop where I was, did all the mechanical work for a rich business man, Carl Linder. Most all his cars, limos, etc, were kept in his downtown parking garage, climate controlled. He had several Stutz Blackhawks and Bearcats that were only a few years old at the time. They were built on a Pontiac Bonniville chassis. At 5 years old, they looked 20 with the rust.

Most of his cars only lasted about 5 years before they needed extensive rust repair body work. I learned from the parking garage attendant that anytime any of the cars are driven and returned, they are washed, dried, and parked for next time out.

It took a heavy toll on all his cars. His Limos took it the worst.

Personally, I use detail spray between washes. I try never to wash the car and just put it away. Many car-soaps today actually help maintain the shine and wax protection already on the paint. A car wash may be different, they are only concerned about immediate results.

James