If you live in a region (country) where your car is regularly exposed to corrosive factors – where roads are salted, near the sea, in regions with heavy industrial pollution, acid rain, etc. – you should take special measures to prevent corrosion. In winter, spray the underside of your car with a jet of water at least once a month and rinse it thoroughly after the winter period.
When washing the underside of your car, pay special attention to under-fenders and other hidden parts. Do the job thoroughly. Simply washing rather than thoroughly cleaning away accumulated dirt can actually accelerate corrosion rather than prevent it. Pressurized water and steam are effective in removing accumulated dirt and corrosive materials.
When cleaning lower door panels, reinforcements and frame parts, make sure the drainage holes are clear so that moisture can evaporate and does not collect inside, accelerating corrosion.
Keep your garage dry. Don't leave your car in a damp, poorly ventilated garage. This creates excellent conditions for corrosion. This also applies if you wash your car inside the garage or drive a wet, snow-covered or muddy car into the garage. Even a heated garage can promote corrosion if it is poorly ventilated and moisture does not evaporate.
Keep paint and trim in good condition. Scratches or chips in paint should be touched up with touch-up paint as soon as possible to reduce the risk of corrosion. If bare metal is found, it is recommended to take the vehicle to a paint shop.
Don't forget about the interior. Moisture can collect under floor mats and carpeting and cause corrosion. Check periodically for moisture under floor mats and carpeting. Be especially careful if you are transporting fertilizers, cleaning materials or chemicals in your vehicle. Such materials should be transported in special containers and any spills or stains should be washed off with clean water and dried thoroughly.
Content based on information from (Mazbook)