Driving in the rain recently, I checked my side mirror before overtaking…except that the door window was so misted up and covered in rain droplets that the mirror was invisible.
Today’s invention is a windscreen wiper for one’s side window(s) in a car. This could take the form of a horizontal rubber blade driven by the window motor -but independent of the usual window movement.
A better solution might even be an ‘airblade’ system capable of blasting a curtain of air down the side window as well as down the mirror surface itself.
The air speed would be sufficient to rid both of surface moisture very rapidly and thus make manoeuvring in wet conditions much safer..