I've got AutoWindows on my, an it's well cool.
I've got the Vent option, and it's perfect for those hot days when you're in the office.
Just set it up when you get in, and it'll vent the windows about 1inch when it gets too hot in the car, and then close them again if it gets too cold, or rains or gets too dark...it more expensive than the KVW100, but still a good option.