Based on recommendations I saw, I bought 303 Aerospace Protectant. It makes these black plastic areas look good just for a day. After that, it makes the surface spotty and the black protectant is uneven. I have tried it a number of times with multiple layers without success.

I bought Black Wow (from detailersdomain) and that's probably what I'll try next. Going to be cautious though as I am concerned that it may be shiny.