As the temperatures drop, many of you will no doubt find yourselves sitting in your freezing cold car waiting for the windscreen to clear up so that you can set off for work.
But it turns out you're best not leaving the engine idling as you do so, as this could land you with a hefty fine.
According to CarMoney engine idling is illegal under Section 42 of the Road Traffic Act 1988.
This enforces Rule 123 of the Highway Code, which states: "You must not leave a vehicle's engine running unnecessarily while that vehicle is stationary on a public road."
CarMoney says: "Those waiting for their cars to heat up on a cold winter's morning could be idling their cars for anywhere between 5 to 15 minutes while their windscreen clears.
"Plus you could risk a fine if you leave your car unattended while it warms up!"
It warns that breaking this law can result in a £20 fixed-penalty fine, but that this also rises to £40 if not paid within the timeframe.
The website adds that local councils may slap an additional fine on top of this, giving the example of emission measures in London, which would escalate the total to £80.
Andrew Marshall, Marketing and Partnerships Manager at CarMoney, said road users could either cover their windscreen overnight to stop it frosting over, or use a can of de-icer and scraper before you need to leave.
He said: "Now more than ever it is important to be aware of our impact on the environment.
"By minimising car idling on our daily commutes, school drop-offs and simply waiting in traffic, we can contribute less CO2 emissions.
"Aside from switching to electric vehicles or hybrid car models, motorists can be more mindful of their idling habits by switching off their engine if waiting for long periods of time.
"As winter approaches, lessen the need for idling whilst waiting for the windows to defrost by covering your windscreen overnight, or using a can of de-icer and a manual scraper to clear the windscreen."
Along with defrosting cars' windows, CarMoney listed six other times that motorists tend to leave their engines idling, including at drive-thrus, at car washes, on school pick-ups, while looking for a parking space, waiting at train crossings or when stuck in traffic - many of which can be avoided if people safely turn off their engines if they've stopped.
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