I've heard they are working on windows for cars whose tint can be turned on and off with a switch. In this case, if you did a 1 foot by 1 foot portion of the windshield directly in the path of the drivers view, press a button, and just that small area on the front windshield exactly where the driver looks out would grow darker in tint, reducing the glare of the inconsiderate or sleepy driver. Once the vehicle passed from view you could disengage the tint and return to normal. ?

Actually I have worked on a aircraft that has that ability but I think polerization would be better since you can see out just as clear as normal with no tinting of windows. Also the advantage may be that on a hot day where you get mirages on the road this may allow you to see through it like with polerized sun glasses being able to see into water that was otherwise too bright. The caveate would be that the headlights would also have to be polerized at about 30 degrees to make this work. Polerization of the windsheild would not be enough.... Hummm are windsheilds already polerized? if so maybe I can conduct a experement...

Polarization of windshields and headlights was proposed shortly after polarizing sheet became available in 1939. For some reason, it never took hold.