When you see how touchless car washes clean cars, you may not want use them much more on your nicer cars.
How can a touchless car wash system remove road grime, that if I used high pressure spray and soap will absolutely not come off? Answer - they use strong acids.
Those acids if left on the car will eat away just about anything. One of the more noticeable problems is with clear coat being eaten off wheels behind wheel weights. A little bit of the car wash water will sit behind the wheel weight and over time it will dissolve the clear coat. GM has a bulletin describing all the damage that can be caused by touchless car wash acids.
One way to tell if their acids are on the strong side. Look at the exit drive and road right in front of the car wash. If it is constantly getting pot holes, their acid dripping off cars is tearing up the asphalt. I had one near me that the road was rough as heck right out front of the wash, but they had installed a concrete exit drive. All other areas of their lot and entry drive was asphalt. They obviously know the acids dripping off the cars will tear up the pavement.