I found a bottle of this stuff in my garage. It's supposed to renew the finish on old black plastic that's been faded by the sun. I figured I'd give it a try. I think they redesigned the bottle since whenever my dad bought this one.



Here's a before and after picture. The picture doesn't do it justice.


Note that in the picture of "after", it's dry (it was a day later). It gives it a bit of a gloss. This stuff works amazingly well. I only had enough in the bottle to do the sideskirts (like a cap-full). If I had more I probably would've done the mudguards as well.

 

This is what I used to do before I got my side skirts painted:
1. Clean the car.
2. Dry the car.
3. Clean my wheels.
4. Spray tire shine on the tires.
5. Spray tire shine on the side skirts.

For those of you that use tire shine, it makes the side skirts look amazing. The tire shine gave them a nice black gloss.

It worked for me so maybe it will work for you.

 

If its outside the car clear coat it. Inside put some tire wet on it.