Penetrol. Found at local hardware store (Home Depot for me)
I used it on my Jeep fenders (notorious for fading).
They look new now. I used it on all plastic parts of the Jeep.
The Xterra hasnt started to look bad, so I havent tried it yet.
This is used to restore oil based paint I think.
Many Jeep guys use it for thier fender flares and hard tops.