I used Back to Black on my 97 4ruunner several years ago on the black plastic running board trim...it was almost white...it worked extremely well! It took a few days of working it into the plastic...looked like new after.

On my 05 Screw, it doesn't work at all...Bed Rails, mirrors...it doesn't touch it...

I have tried the new B2B Cleaner also...no help!

FWIW!

 

threw my Back to Black out, it would streak on the paint after a rain then it would look like crap on the dark paint