1965 Dodge Dart Charger
I owned a '68 Barracuda convertible that originally had a black interior. I changed it to pearl white seats and door panels.
The rear panels on those cars are hard plastic and the original panels on cars with a white interior appear to be a low gloss white with no pearl effect.
I wanted my rear panels to match the pearl white door panels so I found some pearl white paint for a late model car and shot them with that. The pearl effect wasn't quite noticeable enough so I added some old school white pearl to that and it came out just right. Sorry I don't have a pic of the interior that shows the rear panels.
So you might be able to have some white pearl paint mixed with the plastic and vinyl additives and use that on your hinge covers.
Good luck,
Dallas