Hi - my car is awash with gadgets, sponges, kitchen roll - all to try and keep my back plastic window from misting up in the winter.  It's extremely badly scratched anyway, and I'm virtually driving blind from a rear view point of view at the best of times....without having it mist up too.  I've just bought a de-humidifier bag from Halfords, and that's filled up with water over night - but the anti fog wipes I bought are absolutely useless.  Didn't help at all.  Ideally I'd like a new plastic window - but the fitting would cost an absolute bomb I've heard - even if from an old StreetKa spares dealer - I've heard the fitting of a new window or roof is very time consuming.

Has anyone got any suggestions as to how to try and keep the back window from misting up?  I find myself having to pull over every 5 minutes when it's really bad, despite having the heater on, and window slightly open.

Are any of your carpets damp?  Usually when windows keep fogging up like that it's because there's water inside the car.  With a cabriolet I'd suspect a roof leak.  If you stop the leak, the windows should stay much drier!