Fleet News

Fuel economy drops twice as much in hybrids with air con on

Air conditioning systems have a bigger impact on the fuel economy for hybrid vehicles, compared to petrol and diesel models, according to research by Emissions Analytics.

Testing carried out at the company’s facility in Los Angeles has found that driving a hybrid passenger car with the air conditioning turned fully on reduces mpg by an average of 6.1% – almost double the average reduction recorded in petrol engine cars which amounted to 3.8%.

The average mpg in diesel cars was found to be reduced by 4.6%.

The data, compiled by comparing more than 100 passenger cars, also highlights the impact of using air conditioning on fuel economy during motorway and city driving.

The tests found that hybrid models perform worst in both conditions, with air conditioning on average reducing mpg by as much as 9.3% when driven in the city and 2.8% on the motorway.

Air conditioning was found to have the least impact on petrol engine cars in both test scenarios, as mpg was reduced by 5.1% during the city drive and 2.7% on the motorway drive.

Again diesel engines were found to be somewhere in the middle, with results showing an average reduction in mpg of 6.4% in the city, compared to on a motorway which amounted to a reduction of 3.3%.

Commenting on the findings, Nick Molden, founder and CEO of Emissions Analytics, said: “While these results were based on tests conducted in the United States where the climate tends to be warmer and there is therefore larger requirement for air conditioning, our findings can still be applied by consumers in the UK when looking for their next car.”

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  • Scott Brownlee - 15/07/2014 14:16

    Let's see the data. And who funded the research?

  • Alex Thomson - 15/07/2014 14:22

    My Prius 2 "57 reg" averages 57mpg with air-con switched on and driving briskly so am happy with that.

  • Bob - 15/07/2014 15:03

    I agree, lets see the results before we start asking people to turn the AC off. If true I would still have the AC on all the time even if it costs 5% on fuel costs.

  • Darren - 16/07/2014 10:47

    Interesting. Some years ago I rented a polo 1.2 with AC, with the AC on I used half a tank of fuel in about 20 miles! With AC off, the fuel economy was in the 40mpg range around town. On myy 53 reg Nissan X Trail 2.2dCi, there is almost no difference between running with the AC on and the AC off, I am told that the AC has less affect on TD engines due to their higher torque output, which makes more sense than this survey.

  • ReliantRegal - 24/07/2014 10:28

    What about those cars where the air conditioning is fully electric as in some, but not all, hybrid vehicles? The test doesn't seem to make any specific reference, but I'd be interested to know if there was a difference between hybrids whose air conditioning can run without sapping power from the engine. Additionally, no one ever seems interested in monitoring how someone's driving characteristics change if they choose to drive with the windows open (and the impact that might have on aerodynamics and fuel consumption), and the risk to driving behaviour and safety that an uncomfortable cabin environment could create.

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