Where there’s metal, there’s the constant worry of oxidation and corrosion. And when it concerns vehicles, you can’t be too careful to prevent your car from rusting. Rust (electrochemical oxidation) — a simple reaction of oxygen, water vapor, de-icing salt, etc. with your car’s steel — is capable of causing bad damage. This is why cars are painted for corrosion protection with a primer coat, base coat, and clear coat.
As for the other parts of the car, like the frame, cross members, etc., they’re electroplated during the vehicle manufacturing process with a zinc-based primer (owing to zinc’s slow corrosion rate).
If you manage to keep the coatings from getting rubbed or cracked off, your car can remain rust-free. A few things you could do to keep the coating intact include waxing your car four times a year — once each season (a wax or polish product works great), taping over scratched or bumped areas with masking tape and spraying them with a clear coat (a temporary fix to stop rust), and using rust-preventative paints to stop mild rust from progressing (especially on the car’s frame at the bottom).
The purpose of taking good care of your car isn’t just to keep it looking as good as new, but also for corrosion protection – to protect the metal from rusting and causing greater damage.