At the risk of repeating myself, I have not used a commercial car wash (or dealer) once the car is PDI'd and I take ownership. I am fortunate that I have the ability to wash my own vehicles at home. I use the same car wash soap that is made by the brand of wax I use (currently McGuire's Gold Class carnuba/polymer), use a soft lamb's wool mitt with the soap, rinse, strip beads off horizontal surfaces with a chamois and then dry with a microfiber towel to eliminate water spots. I don't wash in the sun or windy days because the tap water is high in calcium carbonates which will dry and water spot if you don't get it dried first. By using a mitt, I avoid the buildup of pollutants on the surface and rarely, if ever, need to clay bar before waxing unless I encounter tree sap somewhere.