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Press releases

The cold truth about winter idling

The Institution of Engineering and Technology (IET)

6 min read Partner content

Warming up your car during the colder months has a higher carbon impact per year than the population of Cardiff flying to Egypt.

  • Motorists leave their cars running for 244 minutes every winter - generating over 107,000 tonnes of CO2 annually in the UK
  • Motorists with a petrol or diesel vehicle are squandering a combined £188 million on fuel costs whilst idling over winter
  • Transition to EVs critical but over half of motorists (55%) who were planning to buy an EV in the next two years, are now delaying because of finance concerns

Warming our cars is no idle matter according to new research out today. 

The average UK motorist leaves their car running for 244 minutes every winter - generating a combined 107,000 tonnes of CO2 annually in the UK[i] – more than the whole population of Cardiff catching a flight to Egypt for COP27.[ii]

The study by the Institution of Engineering and Technology (IET), found that six in ten (64%) drivers let their engine idle during the colder months, with 41% 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.[iii]

Highlighting the extent of the issue, the average idle time during winter is 4.79 minutes but one in six (15%) motorists leave their car running for at least 10 minutes - to get everything – including the 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 have been attributed as the solution to reducing emissions, two-thirds (66%) 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 (55%) 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 327,500 tonnes of CO2 every year.[iv]

Seven in ten (71%) of the drivers questioned said they were more likely to make the switch to electric if government grants were reinstated and 67% 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 £188 million[v] on fuel costs whilst idling over winter – enough to pay for more than 75,000 homes to be heated for the whole year.[vi]

This holds a sense of irony as one of the biggest challenges is the common misconception that motorists need to warm up their car on a cold day. An overwhelming 65% of the drivers questioned had heard this anecdote with four in ten (42%) believing it helps extend the lifespan of the car engine itself.

Commenting on this issue, Farooq Yaqub, Member of the IET’s Council and EV expert, 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 (EVs) 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, 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 motorway journeys.

To find out more about your winter idling carbon footprint and electric vehicles, visit IET’s social channels - Instagram, Facebook, Twitter, LinkedIn.

[i] According to the IET research, the average UK motorist spends 14.35 mins per week idling – the equivalent to 244 mins across the whole winter (November, January and February).

The average family estate car emits 17.60 g/min when idling (

Therefore each motorist emits 4.29kg (17.60g x 244 mins) idling every winter.

There are 39.2 million licensed vehicles in the UK and 64% of these idle which is the equivalent to 25 million (

4.29 kg x 25 million drivers = 107,250,000 kg/107,250 tonnes of total CO2 emitted idling every winter.

[ii] A London to Cairo one way flight emits 241kg of CO2 per passenger (

Population of Cardiff is 362,400 (

362,400 x 241kg = 87,338,400kg/87,338 tonnes of emissions

[iii] The average UK motorist spends 14.35 mins per week idling / equivalent to 746 mins per year

746 x 17.60g = 13.1kg emitted every year

If the average driving lifetime lasts 63 years, this would emit 825kg (13.1kg x 63) in the course of that time


[iv] The average UK motorist spends 14.35 mins per week idling / equivalent to 746 mins per year

746 x 17.60g = 13.1kg emitted every year

13.1kg x 25 million (the number of UK motorists who idle) = 327,500,000/327,500 tonnes

[v] Idling can cost up to 3p a minute (

If the average driver spends 244 minutes idling ever winter, this would cost them £7.32 each (244 x 3p)

If there are 25.8 million drivers in total who idle, this adds up to £188,856,000

[vi] Based on the £2500 average yearly energy bill (,winter%202021%2F22%20price%20cap



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