The place I go to has a very simple heat test. It's a box with a stationary heat lamp inside an enclosure with different brands of tint on glass panes. I prefer this over the false claims of heat rejection in the literature. The Huber Optic ceramic 40 rejected a tremendous amount of heat beating some brands premier metallic 35, 30 and some 20's. They didn't have a comparison to other ceramics though. The only thing I don't like about the Huber Optic is it's coloring. The 40 has a greenish tint, but it cooled our minivan down tremendously.