A. Colorsteel and aluminium products are designed to be low maintenance and durable, but they still get dirty just like any other material, including wood.
The best way to clean your garage door without harming the surface is to mix one part household soap or gentle detergent with five parts water and use a soft, clean cloth to wipe the surface down. To keep your garage door in top condition, you will probably want to consider cleaning it every six months.