Our community members are treated to special offers, promotions and adverts from us and our partners. You can check out at any time. More info Drivers who make a hot weather driving mistake face an £80 fine - and potential anger from other members of the public. Bank holiday Brits are braced for a mini heatwave at the beginning of May, with the Met Office saying there’s a chance of warm weather across the UK. With the mercury rising, vehicle air conditioning systems will be called into action. But if you leave your car engine running while parked in order to keep the air con nice and cold, you could be hit in the wallet.Fines vary between local authorities, but failure to turn your engine off when asked to do so by a ‘relevant officer’ - ie, a council traffic warden or police officer - will see you slapped with an immediate £20 penalty, which rises to £80 if not paid on time. The law exists to prevent any unnecessary ‘noise’ or ‘exhaust emissions’. Engine idling is also said to produce twice the amount of noxious emissions compared with a car that’s moving, as it will burn fuel much less efficiently. Graham Conway, Managing Director atSelect Car Leasing, said: “With most typical cars, the air conditioning system ceases to operate properly when the engine is turned off. You can go from feeling crisp and cool to clammy and uncomfortable in a matter of minutes, particularly during the spring and summer months. “But while it might be tempting to leave the engine idling while your parked, particularly if a friend or family member has just nipped to the shops or if you have a young child asleep in the back, it’s a bad habit we all need to be mindful of. “Most motorists take a dim view of those who unnecessarily idle their engines and you risk a stern word from passersby. What’s more, it’s also an offence under the Road Vehicles (Construction and Use) Regulations 1986 act which could see you hit with a fine. “Of course, there is one way to get around the problem - drive a modern electric vehicle. An EV’s air con is powered by the vehicle’s battery, with no harmful emissions at the tailpipe.” The Highway Code says you ‘MUST NOT leave a parked vehicle unattended with the engine running or leave a vehicle engine running unnecessarily while that vehicle is stationary on a public road’. It adds that if the vehicle is stopped for any more than a couple of minutes you should ‘apply the parking brake and switch off the engine to reduce emissions and noise pollution’. However, it is permissible to leave the engine running if the vehicle is stationary in traffic or if you’re trying to diagnose a fault. Fines can only be handed out on ‘public roads’ - meaning you can’t be prosecuted for leaving the engine running on your own private driveway. But supermarket car parks are something of a grey area. Many are designated as ‘public places’ as the public has access to them, which means you could still fall foul of a relevant officer who takes exception to your engine idling. Select Car Leasing’s Mr Conway adds: “Turn your engine off and open the windows instead. You’ll save yourself from a telling-off and a potential fine.”