This was recommended to us as a way to ease keeping our windshield clean when pulling a trailer. However, on first use it did a lot more for us than expected. The first time it rained after I used RainX was on a cross-country trip last week, and amazingly it almost completely eliminated the need to use windshield wipes even during downpours. Water drops still land on the windshield, but immediately rolls off whenever the car is moving, leaving a very clear view through the windshield - much clearer than even with wipers on high. For those who have flown small planes, the effect is much the same, and why such planes don't even have wipers. (At air speeds, wind pushes raindrops off the windshield very nicely all by itself.)