Well.. i got a responce from the lady at PPG.

She said that the stuff works well on items that arent out in the sun a majority of a day. She said the chemicals wear out, and if they were on a part of a car for example she said they would only last a few weeks before they wouldnt work any longer.

Electro-chromic is the only way to go... $$$


Photochromic tint would totally kick azz tho.