Winter idling of car engines creates high carbon cost

Warming our cars up in winter before driving away is no idle matter, according to new research shared by the IET. 

The average UK motorist leaves their car running for 244 minutes in winter – based on an average idling estimation of 14.35 minutes per week over three winter months – generating a combined 107,000 tonnes of CO₂ annually in the UK. This equates to more than the entire population of Cardiff catching a flight to Egypt to attend COP27.

The study by the IET found that more than six in ten (64 per cent) of drivers let their engine idle during the colder months, with 41 per cent doing so at least three times a week. More than a million motorists idle every single day during winter, producing a carbon footprint over a lifetime of 825kg.

Highlighting the extent of the issue, the average idle time during winter is 4.79 minutes, but one in six (15 per cent) motorists leave their car running for at least 10 minutes merely to get everything – including the vehicle interior – warm.

The research, undertaken ahead of COP27, highlights the whole-scale change required to meet the government’s 2030 net-zero goals. Although electric vehicles (EVs) have been hailed as a major solution towards reducing emissions, two-thirds (66 per cent) of motorists said it was highly unlikely they will be driving one before the government’s ban on the sale of new petrol and diesel cars comes into effect in 2030.

Over half of motorists surveyed (55 per cent) who were planning to buy an EV in the next two years are now delaying doing so because of concerns about their finances – a decision that could accumulate a further 327,500 tonnes of CO₂ every year.

Seven in ten (71 per cent) of the drivers questioned said they were more likely to make the switch to electric if government grants were reinstated, while 67 per cent said they would buy an EV as their next car if money wasn’t a factor.

Proving it’s not just the planet that’s worse off, motorists with a petrol or diesel vehicle are squandering a combined £188m on fuel costs while idling over winter – enough to pay for more than 75,000 homes to be heated for the whole year.

A major challenge in reversing the practice of idling is the common misconception that motorists need to warm up their car on a cold day. Almost two-thirds (65 per cent) of the drivers questioned had heard this anecdote, with four in ten (42 per cent) believing it helps to extend the lifespan of the car engine.

Commenting on this issue, Farooq Yaqub, an EV expert and a member of the IET’s Council, said: “It only typically takes less than 30 seconds to lubricate your engine once running and when driving your engine should quickly reach full operating temperature. Excessive idling can also actually damage your engine’s components, including spark plugs, cylinders and exhaust systems – and an idling engine can produce up to twice the emissions of a car in motion.

“The transition to electric vehicles will be so critical in the long-term in helping reduce emissions from petrol and diesel engines. Yet the research has demonstrated a clear financial barrier to this being a straightforward process, amplified by the cost-of-living crisis.

“This is why it’s so important that the government provides further support and incentives for EV uptake if they are serious about meeting their 2030 net-zero goals.” 

To help Britons save money and the planet in the meantime, the IET has developed some top tips to help lower motorists’ winter idling carbon footprint. 

• De-ice your windscreen. You can remove frost or snow without having to warm up your engine by using an ice scraper and de-icer.
• Myth busting. You do not need to warm up the engine before driving in your car. The operating temperature is quickly reached and the emissions management devices are active in the meantime.
• Park inside. If possible, park your vehicle inside, such as in a garage, to avoid frost build-up and to ensure a more comfortable temperature when you first get in.
• 10-second rule. If you’re going to be stationary for more than 10 seconds, it’s best to turn off your engine; restarting does not increase fuel consumption. Alternatively, if your vehicle has a start/stop feature, as many models do today, make sure it is turned on.
• Route optimisation. Use real-time navigation apps to help you avoid traffic and thus spend less time idling. Occasionally driving slightly longer distances at more consistent speeds will not only get you to your destination faster, but will also help the engine run more efficiently.
• Right tool for the job. Diesel and gasoline vehicles have distinct characteristics and using them for appropriate applications is critical to achieving higher efficiency and lower emissions, i.e. diesel vehicles are more suited for long motorway journeys.

The research for the IET’s survey was conducted by 3Gem in October 2022 and involved 2,000 UK motorists aged between 18 and 65. The analysis and calculations were made drawing on data and statistics from previous studies from reputable sources e.g. City of London, the UN, the Office of National Statistics and Gov.uk.