I scrubbed with dish soap on our 2002 grilles and then shot SEM Trim Black, they look very nice.
If the surfaces are in good condition but just faded then cleaning them and repainting is a simple and inexpensive way to make them look like new. A similar product to the SEM paint is Dupli-color Trim and Bumper paint. It's available in many auto parts stores. You will have to mask the polished trim or remove before painting.