Our Corsa, due a steep sloping windscreen is very prone to misting and even icing in winter. Having tried this heater out I can report it seems effective enough and should be a big boost to the car's own efforts. Not deepest winter yet of course. Only slight problem is I think it will be a big draw on the battery, but this would be true of any plug- in and instructions do include, use only when engine running. It must be either screw fixed or you need a fairly flat part of the dashboard, I use one of those non slip mats and everything works ok. Seems well enough made.