The materials of automobile rear fender usually include the following:

1. Plastic: The plastic rear fender is light and durable, with good impact resistance and corrosion resistance and low cost. Plastic rear fender is usually used for city cars and small cars.

2. Polyurethane: The rear fender made of polyurethane has good elasticity and wear resistance, which can effectively absorb collision force and reduce damage. Polyurethane rear fender is usually used for off-road vehicles and SUVs.

3. Carbon fiber: The rear fender made of carbon fiber has light weight, high strength, excellent impact resistance and good appearance. Carbon fiber rear fender is usually used for high-end luxury cars and racing cars.

4. Aluminum alloy: The rear fender made of aluminum alloy has good strength and corrosion resistance, and is light in weight, which helps to reduce the overall weight of the vehicle. Aluminum alloy rear fender is usually used for sports vehicles and modified vehicles.

5. Steel: The rear fender made of steel has high strength and durability, which can effectively protect the chassis and mechanical parts, but it is relatively heavy. Steel rear fender is usually used for commercial vehicles, off-road vehicles and other vehicles that need stronger protection performance.

To sum up, the materials of automobile rear fender mainly include plastic, polyurethane, carbon fiber, aluminum alloy and steel, etc. The rear fender made of different materials has different characteristics and application scope, and the owner can choose the appropriate material according to the vehicle model and demand.