This'll be my 8th winter with the Zed so I've had quite a bit of experience with this. Personally, I don't worry about the windows, the main battle is actually to get the doors open. They usually freeze in the area around the door handle/door lock so its O.K to use hot water in that area, as for the windows, they may or may not freeze, I don't really know as I don't want the windows down when its freezing outside .Be aware that in a prolonged freeze your headlight washer covers could pop out (both mine and my wife's did anyway). I don't know what other Zed owners do about this but I feel its best to fix this using warm water just in case the washer cover flies off when you're driving along.
Pete
Thanks for the tips Pete. I know what other things to watch out for now, when it gets really cold.