NY wrote:

What about those water-repellent coatings that you can have applied to
your windscreen and side windows so the rain forms globules which blow
off the screen


they're ok, providing you realise when you start using rainX or
whatever, you've got to keep applying them, if you stop you end up in a
worse situation where it doesn't clear by itself and it goes streaky if
you do try to use the wipers.