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Plug-in hybrid electric vehicles produce nearly 5x more global warming emissions than lab-reported figures show, as per a recent report.

Widening Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a advocacy group. This contrasts sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers examined data from onboard energy use monitors of 800,000 vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a lead analyst participating in the report. “That gap is widening and poses a significant problem. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric mode relative to total mileage. The team found that just 27% of travel was done in electric mode, while lab estimates suggested 84%.

Additionally, when running in electric mode, emission levels were significantly higher than official estimates. That occurred because electric motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for almost one-third of the travel covered in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed four large automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more per year in operating costs than would be assumed under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn again into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the car sector and opposition from EU countries with significant car industries.

Several senior officials have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful addition” after a long period in which parts of the automotive sector argued there was insufficient information to properly assess actual emissions.

“These findings demonstrate, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme care and in the light of that evidence.”