Am I the only one who thinks that they are very difficult to notice on the glass even after 5 minutes of driving with the wipers off? I'm talking about light rain. During a storm, they are noticeable. Maybe because they are too small or too clear/transparent.
It works on some trains (like the Flying Scotsman) but it really doesn't on the Class 801. This is not helped by the fact that the Class 801 can actually outrun the rain in-game.