I've used this product for over twenty years.  Motorcycle windscreens, motorcycle helmet face shields, and pretty much any clear plastic things that you need to see through...this is the product that extends their lives.  Nowadays, of course, we have clear plastic headlight covers.  Our modern headlights are plastic, on the front of the car, and often pretty low to the ground, subjecting them to nonstop pelting with sand, grit, road grime, and trace solvents sprayed up from the road in the rain.  A perfect cocktail for grinding the smooth finish into matte.