Prevent frost on car windscreens by rubbing 1 food item on the glassMotoring experts have shared a unique de-ice and de-mist method involving rubbing a vegetable on windscreensView 3 Images Elderly man cleans windshield from snow with ice scraper. Frost on a car. Driving in winter season conceptIcelandic motoring experts have suggested a unique method for de-icing and de-misting car windscreens: rubbing a potato or onion over the glass. Lotus Car Rental claims that these vegetables can break down frost as soon as cold weather begins to form on a windscreen or window. ‌This simple trick could also prevent condensation from forming on the glass, allowing motorists to hit the road faster this autumn and winter.