window vent visors are fairly common. "i" have experienced that any rain or windshield washer fluid on the windshield will sweep across the carand along the side, and flow in the front windows if they are open.
i don't drive with the windows "full" open, but i like to leave about a half inch. (i smoke and would like to ventilate the smoke).
if you park your car in a hot climate, it is commonly suggested, that you leave at least 1 window open slightly, to help minimize heat build-up. if a thunderstorm or rain shower should occur, that portion of the car can be soaked.
i have experienced all four door panels being soaked with rain flowing in the car, and would like to prevent that.
a trip to any auto-parts store or web site, might help you see that they are available for most makes and models, and they sell quite well. if you see the need or not, that is up to you, i posted a link that might help someone else who asked, just as i would for you if i could help you find something, that you needed or was interested in