Modern cars have 3 coats of paint on the bare metal: Primer or base coat, color and clear.
Contaminants are the largest contributor to having the clear coat paint layer break down exposing the color coat and eventually bare metal. Here is how the process occurs:
Here are some examples showing extreme clear coat breakdown. Once this process begins there is no alternative but to repaint the surface. Waxing, polishing, sanding will make no difference. Most of the time it begins with the top, hood and rear deck.
The idea of course is to prevent this from happening by keeping the car clean and free of contaminants, and periodically applying a wax or sealant of your choice.
The first step is to wash the car with a PH balanced soap formulated for auto paint and a clean soft micro fiber pad or sponge. These soaps have special lubricants that lift dirt from the surface allowing you to wash without creating additional scratches. If you use dish washing liquid from under the kitchen sink, it can remove any wax or sealant from the surface that you have worked hard to apply.
Be sure and dry the car with a chamois or a soft micro fiber drying towel while it is still wet to prevent water spots. I advise against using household cotton towels because they can scratch the paint. Here is what your car's paint surface looks like after washing:
Notice the contaminants that remain. The next step is to remove these surface contaminants by using paint cleaning clay. Clay comes in bars and you massage the paint with the clay along with a special lubricant. Here is a before and after picture:
What you have left are below surface contaminants (which can be removed with a special Iron - X solution) and surface scratches, swirls, acid rain or hard water spots. Bug "jerky" and bird droppings can also cause pits in the clear coat and even your windshield if left on the surface too long. The way to remove theses paint imperfections is to use a compound or polish. Unless you are skilled in using these substances, I advise you to have a professional perform this part of the process.
After your have cleaned your car, removing contaminants and polishing to your satisfaction, apply a wax or sealant of choice. Waxes generally last 2 to 3 months and sealants can last form 6 to 9 months. I recommend using a sealant in the fall of the year to protect your car through the winter months, especially if you live in colder climates where washing and waxing are more difficult.
So get out there and have some fun and clean and wax your car. To me a clean, shiny car runs better and it sure looks better.
If you have any questions you can email me at firstname.lastname@example.org.