Corrosion (Rust)

Modern cars use galvanised steel and coatings to resist rust. Typical rust spots are wheel arches, sills, doors and brake lines. Structural rust can fail inspections. Surface rust only affects the paint and outer layer; rust that perforates panels or weakens load-bearing parts is serious. Cavity wax and drain holes help keep inner panels dry.

Water and salt create an electrochemical reaction that turns iron into rust.

Wash underbody in winter and repair paint damage. Rusted brake lines or suspension mounts are safety risks.