Plasti Dip is good, but it isn't permanent, it is meant to be fully reversible. You only need to do one coat with it... They do make stuff called plastic restorer designed to restore black faded plastic, I've never used it, but I've heard good things about it...
2000 Ford Focus US Spec Zetec 5 speed "Blue Dragon"
2000 Renault Clio 1.4 DOHC 5speed "Snap Dragon"
Hatch Nation #32