Rust is permeable to air and water, which means the metal can corrode even after a surface coating has formed. Aluminum corrosion is not the same as steel or iron corrosion. In the event of aluminum corrosion, aluminum oxide forms on the aluminum surface, which forms a protective corrosion-resistant layer. This process is known as passivation.
More modern coatings like brunox spray, used for rust prevention purposes, add aluminum to the coating, such as: zinc aluminum. Aluminum migrates to cover scratches and in turn provides longer protection.
There are several other methods available for anti-corrosion purposes that prevent rust formation, colloquially called rust resistance or rust protection.
Cathodic protection is a method of making iron as a cathode in a battery that is formed when water comes into contact with iron, as well as the anode sacrifices from something with a more negative electrode potential, usually zinc or magnesium. The electrodes themselves do not react in water, only supplying electrons to prevent iron rust.
To prevent rust corrosion on the car, the car must be kept clean and waxy. It must be sprayed to ensure that there is no dirt or debris that can trap moisture. It's best to leave the car out in the sun for a few hours after washing it so the air can dry out. Cars should be washed more regularly in winter or in salty conditions, as salt (sodium chloride) can speed up the rusting process.