Which part of the car is primarily affected by rust over time?

Rust primarily affects the body panels of a car over time due to their exposure to moisture, road salt, and environmental elements. These panels are typically made of metal, which is susceptible to corrosion when exposed to water and air. Unlike the engine block, frame, or exhaust system—which may also experience some level of corrosion but are often protected by coatings or are made of materials less prone to rust—the body panels are directly exposed and thus have a higher risk of developing rust spots. This is particularly evident in areas where the paint might chip or wear away, allowing moisture to penetrate and initiate the rusting process. Additionally, regular exposure to the elements increases the chances of rust formation on these outer surfaces.