A coated windscreen is the one upgrade people notice the first time it rains. Above about 60km/h the water simply leaves the glass on its own.
Glass is porous, and untreated glass holds a film of road grime, wiper rubber and traffic residue that scatters light. That film is exactly what makes headlight glare so bad on a wet night. Coating the glass seals it, so water beads and rolls instead of sheeting, and the film cannot build up the same way.
We prepare the glass properly first — a clay strip and a polish to remove bonded traffic film and light wiper marking — because a glass coating applied over that film will not bond or last. It is a quick job and it makes a genuine safety difference in a Melbourne winter.