It's only good on things like polycarbonate/lexan or the harder plastics...such as head and taillights. Any plastic with a matte finish ends up glossy. Soft plastics like ABS used in car interiors don't respond to it well at all in my experience.
Sound advice. I hate the glossy finish on the interior plastics.
The other day, my headlight cover was coated with over a 1/2 inch of ice and I was chipping away at it with the ice scraper... Your brain tends to freeze up when it's that cold outside :disappoin ...Looks like I'll be using that PlastX sooner rather then later.