A handy tip on how to get rid of windscreen film. Just add a tablespoon of ammonia per 600 ml of water. It works better than plain old soap and water.
The plastic fittings in most new cars give off fumes. These fumes can cause a haze on the windows. Sponge with vinegar, rinse with water and wipe with a dry cloth.
On foggy mornings, try rubbing a cut, raw potato over the car windows. When it dries it will keep the windows clear.