New Study Claims Some Plug-In Hybrids Use More Fuel Than Claimed: Cheaper PHEVs Used Less Fuel Than More Expensive Ones

   

     German research organization, the Fraunhofer Institute, recently put out a report that claims that some plug-in hybrid vehicles (PHEVs) use more fuel than they claim to use. The study utilized data from about 1 million PHEVs from 2021 to 2023.

     According to an article in This is Money

“Fraunhofer Institute found real-world fuel consumption is 5.9 litres/100km - or 48mpg - which is around 300 per cent above the type-approval consumption.”

“In fact, PHEVs show fuel consumption on the road equivalent to conventional internal combustion cars.”

“Vehicle makers had claimed that plug-in hybrids use hardly any fuel when in electric mode, but the study has shown that this might not be the case.”

     Having owned a PHEV for approximately one year in 2019/2020, I can say quite definitively that the study does not reflect my experience at all. That, however, does not dispute the study, which shows that different PHEVs can have vastly different fuel economy and subsequent fuel consumption.

     A previous analysis by the UK’s Energy and Climate Intelligence Unit (ECIU), an electric vehicle-backing research organization, as reported by This is Money, suggested that PHEV owners were paying twice as much to fuel their vehicles with gasoline and electricity as they were led to believe. The study also noted that PHEV sales have skyrocketed in the UK, increasing by 34% and outpacing new diesel vehicles by more than double. See the second graph below. The study claims that PHEV owners typically don't charge their cars regularly enough to make the most of the electric benefits. However, I can clearly say that was not the case with me.

     The new study by Fraunhofer Institute concludes that higher-than-stated fuel usage is due to PHEVs switching between modes - the electric motors and the combustion engine. The study suggests that the gasoline engine engages more in “discharge mode” than previously believed.

“It turns out that many cheaper PHEVs from brands like Kia, Toyota, Ford and Renault have the lowest fuel consumption.”

“These plug-in hybrids typically used under one litre per 100km - the equivalent to a staggering 282mpg.”

“On the other hand, Porsche hybrids consume far more fuel - around seven litres per 100km (roughly 40mpg).”

     I had a Kia and calculated my avg mpg somewhere around 75mpg due to the PHEV range of 26 miles and my typical commute, which was about 45-55 miles round-trip. With a shorter commute or a bigger range, I could increase that to about 120mpg. I was lucky enough to have a Level 2 charger installed at home. Others may be compelled to charge at public charging stations, which have higher costs. It may also be inconvenient to charge them at the right times, which may hinder keeping them charged optimally.

     The findings from the report have echoed calls for reforms in the EU and UK, including that PHEV users should be shown the proportion of electric driving transparently on the display ('display transparency') or be forced to charge at least every 500km (311 miles) to reduce their emissions impact. Another policy goal is to get lab-based emissions testing results to better match real-world driving conditions. Of course, if PHEV owners are not charging their vehicles enough due to inconvenience or whatever, then that is their own problem and should not be reflected in policy.

 

  

 

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New study claims plug-in hybrid cars guzzle three times more fuel than advertised. Freda Lewis-Stempel. This Is Money. February 19, 2026. New study claims plug-in hybrid cars guzzle three times more fuel than advertised

Plug-in hybrid cars dubbed a 'scandal' by think tank due to fuel bills double what drivers are told. Rob Hull. This is Money. January 26, 2026. Plug-in hybrid cars dubbed a 'scandal' by think tank due to fuel bills double what drivers are told | This is Money