Used C4 on black bumpers did a really good job - also used autofinesse revive again only used it on exterior plastics:
https://shop.autofinesse.co.uk/revive-250ml
AF Revive is in my arsenal now and has been years. I only currently only use it on a couple of exterior parts too (To make them look really Black and stop the greying of UV infected parts) - where its great ! Didnt work so good on the seats though.
Anyway. After a lot of faffing around and looking at pics online and reading reviews i went for CarPro PERL in the end. Which stands for: Plastic, Engine, Rubber and Leather coat....
1 item sold by rollupandshine
Carpro PERL Plastic Engine Rubber Leather Dressing 500ml 16oz
( 253042061294 )
Estimated delivery Tue, 18 Jul
The real pulls of this product being great finish, good darkening properties and its highly dilutable; meaning it not only goes along way - but different finishes can be had by using stronger / weaker solutions. So if it no use on seats.....i'm sure it will get used somewhere..
Thanks for all your help guys. Looking forward to seeing it in action now @VolumeX