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Plug-in hybrid cars emit almost five times more global warming emissions than lab-reported data indicate, as per a recent analysis.

Growing Gap In Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a advocacy group. This contrasts significantly with lab estimates, which assumed a 75% decrease in pollution.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand cars registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a lead researcher involved in the report. “That gap is growing and poses a serious issue. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery mode relative to overall distance. The team determined that only a quarter of travel was done in EV mode, while lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, pollution levels were well above lab projections. That happened because EV motors were not strong sufficient to function independently, leading to combustion motors burning gasoline for nearly one-third of the distance covered in electric mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed several major automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra annually in operating expenses than is estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the truth,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn back into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with significant automotive industries.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

One independent energy economics specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the car sector argued there was too little data to accurately assess actual emissions.

“The results demonstrate, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be implemented with extreme care and in the light of this evidence.”