CarGlass
This is a material I made in Unreal Engine 4 for a car simulator. The transparent windows were very expensive and had to be optimised. As the car moves away from the camera, the windows change from translucent material to opaque with a dithering effect. The windows then fill in as the windows goes even further.
Here is the same car at a distance, here the windows are much cheaper to draw while they still seem to be transparent.
Here is the material graph:
