There's another product "Black again" that you SHOULDN'T use if you're really close to repainting your vinyl.
It's a clear liquid (so it's definitely not adding color) that works "okay" on plastic/vinyl and gets them darker/shinier but doesn't seem to last that long and needs to applied regularly (as the instructions state).
I bought a bottle and have been using it regularly as a treament on my black trim and tires, too. It gives a nice sheen but if your material is oxidized badly it won't do anything. If your trim is in fairly good shape it seems to work.
I will try Forever Black next time for treating the more oxidized areas.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition