@gjunky That is not an entirely true statement about tunnel washing. Today's tunnel equipment, brushes and chemicals are actually better than hand washing. Why, because the systems rinse the brushes clean before and after each car passes, thus all contaminants are removed from the brushes. Additionally, the chemicals lubricate the surface and help the particulates flush off the vehicles without being rubbed into the paint. but, don't take my word for it. Here is an excerpt write up:
"It has been said that automatic car washes scratch the paint and are harmful to the finish. This is false. A few years ago, Mercedes-Benz had the Technological University of Munich do a comparative study of hand washing vs. automatic washing with “Foam Brite”. In this study, vehicles on the street were washed 26 times to duplicate the number of times a car might be washed in a year.
One test group was hand washed and the other was machine washed.
Upon completion of the test, microscopic photos of the paint were taken and it was found that there was more scratching, marring and damage to the paint of the hand washed cars than those that were machine washed.
Why?
It was determined that when a vehicle is hand washed, the first time the sponge or mitt used to wash the car touches the dirty surface, the minute particles of sand and grit get into it. Each subsequent time the sponge or mitt is rubbed onto the car’s finish during the washing process, the action is like a piece of fine sandpaper. On the other hand, the washing material used at the car was is “Foam Brite”, which is bombarded with shampoo and water during the washing process. This forms a barrier between the washing material and the paint, preventing swirls or scratching. Plus the constant mist of water being shot on the brushes keep them clean of dirt and grit at all times."
