Swirl marks are caused by a number of factors. Improper washing techniques, waxing with a wax that contains too coarse of an abrasive, spinning brushes used when washing, wiping off dust when the paint is dry, waxing while dust is falling on the car from the surrounding air, buffing with a cloth that is not extremely clean, improper use of a buffing machine, vigorously rubbing the paint to remove dirt while washing, etc. No matter how hard you try, you will still get swirl marks over time. The more you wash the faster the swirl marks will appear. The darker the paint the more noticeable they are.
Never run your car through commercial car washes that rub the paint surface with brushes. They may cause millions of fine scratches. Their industrial strength detergents also tend to drive off the wax you’ve taken so long to put on! Automatic car washes are great for the average guy that’s lazy but poison to the perfectionist. We have found that using most types of brushes on paint for car washing can cause fine lines in the wax coating.
You must use a very fine polish to remove swirl marks. You have to do a lot of rubbing by hand or use a machine. It is worth the effort. Properly done, the gloss can actually make your car look better than when it was brand new.