The key to cleaning piano black exterior and interior trim is to use a microfibre cloth to avoid scratching the surface. Most interior cleaning products are designed to work with more sensitive materials and a diluted exterior shampoo will be safe to use on exterior surfaces. Avoiding scratches is key, so be sure to change or rotate the microfibre cloths you use to avoid damaging the surface.

Piano black trim is usually made of plastic, so if you do want to polish the surface ensure you use a product that is safe for use on plastics.