Drivers will break this little-known Highway Code rule every day during winter

Millions of drivers have been warned they will be breaking a Highway Code rule every day over the coming months. The 'offence' in question is to leave your car idling. This means when the engine is left running.

Now many may know you shouldn't leave your engine running while you're not in the car because of the risk of them being nicked. This is something that will be common in the next few weeks as the weather turns icy cold and drivers seek to warm their cars before setting off on journeys.

But what is probably less known is drivers shouldn't leave the engine running while out on the roads if stationary for more than a couple of minutes. This could include being stuck in gridlocked traffic or at traffic lights or roundabouts when progress is very slow.

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According to the code, the correct thing to do in this situation is put on the handbrake and switch the engine off - even if this rarely happens in reality. It's okay to leave the engine running when in traffic which is moving often.

Councils in some areas have started issuing fines to motorists who leave their engines running around schools, amid fears over health risks associated with emissions. The code states drivers "should apply the parking brake and turn off the engine if the vehicle is stationary for more than a couple of minutes".

Experts at Swansway Motor Group explained: "Under Highway Code Rule 123, drivers must not leave a parked vehicle unattended with the engine running unless necessary, such as when waiting in traffic. This rule aims to reduce emissions and minimise health risks. The Road Traffic Act 1988 makes idling an offence, with fines for non-compliance. However, fines may soon increase as councils try to deter idling more effectively."

They added: “A higher penalty would remind drivers of the environmental and health risks associated with idling. As autumn settles in, we should all try to avoid idling as it directly impacts our air quality.

“These emissions contribute directly to climate change and have immediate health consequences. While newer vehicles are designed to minimise emissions, it’s always best to switch off your engine when it’s unnecessary to keep it on.”