Bondo Restore Black! It comes in a kit with an applicator and a bottle of black pigmented gel type liquid. Works great on black plastic trim and lasts quite a while. It DOES have black pigment, so it only works on black plastic trim, but should be perfect for your wiper cowl. My friends couldn't believe I didn't paint mine... Having mentioned that, I recently bought an airbrush, and supposedly airbrushing the black plastic trim is a good solution. I'll find out after I test it somewhere less obvious with some semi flat black.