If you're lucky, your car's paint is still in good condition and you can simply buff out the foggy areas. If the paint is old or damaged, however, you'll need to repaint the entire car. Either way, you'll need to start by cleaning the car's surface with soap and water. Next, use a clay bar to remove any contaminants from the paint. Once the surface is clean, apply a polishing compound to a microfiber cloth and buff out the foggy areas. Finally, apply a wax or sealant to protect the newly polished paint.