Ceramic coatings are not a way to avoid washing your car. Even when newly coated they will extend the time before a wash is needed but just hosing the car will not remove everything and still leaves a fine film of dirt, so if you then dry the car with a towel or chamois you will rub the dirt into the paint and create scratches.There is no issue with using wash and wax. I think the ceramic coating is for lazy people who just want to hose off their car once a week and for it to come out looking shiny.