Well, drove around in my Jeep. Worked reasonably well in the unzipped position, though I had to put small bungees around the rear sail panels to keep them from flapping annoyingly. But once I did that, no flap, and just a nice draft in the front cabin when the front windows were rolled up. Rolled down, of course, was plenty of breeze.
Clouds rolled in, so I decided to zip the windows in rather than risk needing to pull the drain plugs on the bottom of the Jeep. After I did that, it of course turned sunny again. Of course.
-- Badtux the Jeeping Penguin