We shouldn’t let our cars warm up on the drive, says the RAC, since we expose our selves to theft that our insurance won’t cover because we left the car and keys exposed. We also damage the environment and out catalytic converters it’s said.

However, we shouldn’t drive off until the windscreen is clear, the motorists’ organisation said today. It seems we are dammed if we do, and dammed if we don’t. (Though they do offer some tips!)

The new research released by the RAC shows that British motorists are risking their personal safety and causing costly damage to their vehicles by failing to take the correct measures to clear their car windscreens of frost and ice before setting off on a journey.

Apparently, 42% of drivers confess that impatience means they regularly set off on a journey without having defrosted their windscreens thoroughly.

The survey also reveals that icy windscreens are playing havoc with morning schedules causing over a quarter (26%) of commuters delays of up to 20 minutes on their car journeys to work each morning.

Many motorists mistakenly use methods that can result in cracked windscreens and broken wipers:

• Nearly a third (29%) of drivers pour hot water on to the windscreen to de-ice it
• Over a quarter (27%) of motorists have used a credit card to scrape ice off the windscreen
• 43% of car-owners have used their wipers to remove ice or snow from the windscreen.

Furthermore, with as many as 54% of motorists admitting to leaving their engines running in the driveway in order to speed up defrosting of their windscreens, the possibility of theft is also cause for concern – not to mention the environmental impact.

RAC Auto Windscreens highlights the dangers of driving without clear vision and the risks motorists are taking in being penalised. According to the survey, 39% of people are unaware that driving with "porthole" vision can result in a fine of £1000 and driving licence penalty points. More worrying still is the fact that as many as one in ten accidents on the UK’s roads are caused by vision impairment, which can result from ice and snow on the windscreen.

John Tutt, RAC Auto Windscreens operations director, said: “Our research shows that many motorists are taking inadequate and potentially dangerous measures to de-frost their windscreens during the winter months.”

“The most common mistakes to make are trying to clear ice with credit cards or windscreen wipers which can scratch the glass or pouring hot water which can cause cracking. It’s important that drivers take the extra time to prepare their cars for winter conditions safely and ensure that their windscreens are free of ice and frost before setting off on a journey.”

RAC Auto Windscreens winter motoring tips:

• Before setting out on a journey, use a windscreen scraper or a de-icer to remove ice from your vehicle - do not use warm water from a kettle, as resulting problems may include a cracked windscreen 
• Carry a key de-icer with you to clear your lock
• Do not drive with a small hole cut through the ice on your windscreen. The Highway Code states that it is illegal to drive with poor visibility 
• Ensure all windows and mirrors are completely demisted and totally cleared of ice using a can of de-icer and a windscreen scraper
• Check front and rear wiper blades for wear or splitting. Check windscreen washers making sure that they are adjusted correctly. Screen wash additive should be added to prevent freezing in winter.
• Motorists can find out more information on winter driving at the RAC Know How section at www.rac.co.uk