I recently painted all the plastics on an 01 X I just bought, and it turned out well.
On a newer FJ Cruiser I own I wanted to spiff it up recently and ran across a thread on another forum about 303 Aerospace Protectant. A detailer claimed this was the greatest thing he's ever used to refresh faded plastics. I have used back to black, and was not all that impressed with it, and have tried Armorall in the past too. The 303 is hard to find, finally found it at a marine store. It's claim to fame is that it is a UV shield, supposedly. I found a website that said O'Reilly's carried it, but my local store had never heard of it. It was $24 for a 32 oz spray bottle, and the 16 oz was about $16 or so, so this is not a cheap item.
I applied to all the plastics on the FJ, and buffed it off with a dry towel. Very happy so far, but the real proof will be in how it hold up. The detailer indicated that a couple of times per year application will keep your plastics protected form the UV. YMMV