I tried the Wipe New and it didn't work.
I have resorted to just pulling the pieces and painting them.
I am using Rust-Oleum Trim & Bumper Paint in matte black...it has a satin-like finish, not really matte.
The results actually look better than when I got the bike, which had been sitting in the showroom for two years, so the plastics had already started to fade a bit at that point.
I'll post some pics later on when I finish the complete restoration (adding big pannier lids and a Honda top box too).