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Plug-in hybrid cars release nearly five times more global warming emissions than official data indicate, according to a recent analysis.

Widening Gap In Official and Actual CO2 Output

Data shows that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit group. This differs sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” stated a senior researcher participating in the report. “This discrepancy is growing and creates a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery mode compared to total distance. The team found that only 27% of driving was done in EV mode, while official estimates assumed 84%.

Additionally, when operating in EV mode, pollution amounts were well above official projections. This occurred because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning gasoline for nearly a third of the travel covered in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled several major automaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more per year in running expenses than would be assumed under lab tests.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are clearly far from the mark,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Hybrid cars have lately been brought again into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large automotive industries.

Several senior politicians have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

An independent energy policy specialist, who was unaffiliated with the research, called the analysis a “highly valuable addition” after a long period in which parts of the automotive sector argued there was insufficient data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the gap between official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional cars,” they stated. “All policy changes concerning PHEVs should be made with extreme care and considering this evidence.”