I spent about $25 a couple of weeks ago and ordered a 2 kits of "Forever Black" and a couple of bottles of Lexol's "Vinylex." The Forever Black product was supposed to be a dye that restores black plastic trim -- flares, mirrors, hood vent, gas tank plastic piece, front bumper plastic piece. And sure enough, it seems to work as advertised and reviewed. Two coats seemed to get some 16 year old plastic trim looking pretty new, like you just blew a Saturday and a few hundred bucks swapping all your old trim for new pieces .
I'll see how it holds up over time, but it seemed like money well spent for 4banger that isn't trail-only.
The Vinylex stuff is good for tops, doors and interior surfaces. Did a nice job cleaning the hard plastic interior door surfaces. It goes on like Armor All, but doesn't have the shine and does have supposedly decent anti-UV properties. I'm trying to use it to stretch out the life of the top, seats which get a lot of sun.