I think there might be confusion with names.
This site from Hemmings talks about an early 70s musclecar that had "Magic Mirror" paint:
Back in 1970, GM used Magic Mirror acrylic lacquer with no clearcoat. This paint, while easy to polish and wax, was prone to damage from extended time in the sun and acid rain. I'm thinking that you used a product that was a polish for "Magic Mirror" paint, not "Magic Mirror Paint Polish", if you get my distinction.
It is possible (and I don't mean this in in a negative way, just meaning that technology changes over time) that the reason the polish was so good at bringing back the shine was because paints back then tended to fade so quickly!
I can't find anything out there called "Mirror 2000" polish.
Bill