[hayden55]

Not really efficiency of compressor wise but on the Prius this summer I went ahead and did 70% crystalline on the front windshield, and 40% crystalline on the driver and passenger windows. Metered out altogether with the factory tint it netted at 56% front visible, 25% sides visible, 79% energy rejection on the windshield, and 78% energy rejection on the side windows. Also, to save extra money I paid in cash, still got the lifetime warranty in the USA, and skipped tinting the rear windows.
Last summer on short trips around town it was much more bearable to crack the pass window and a rear window for some air flow to avoid using the AC. I honestly never really used the AC around town unless I had somewhere I needed to be a didn't want to be hot when I showed up. Past that I noticed my AC didn't howl as much on the interstate on auto anymore. I could set it to like 73F and not get cold hands and sweaty arms from getting a sun burn and blasted by cold air simultaneously.
I did it in my civic too a long time ago. I drove with the sun constantly on the driver's side so I had them tint the driver's window and got a scrap piece of tint for the front window in front of my torso and hands. Made it a lot more bearable since the AC cooled maybe 2 degrees. lol