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Plug-in hybrid electric vehicles emit almost five times greater planet-heating emissions than official data show, according to a recent analysis.

Widening Discrepancy In Official and Actual Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit organization. This contrasts sharply with laboratory tests, which assumed a 75% reduction in pollution.

Analysts examined data from onboard fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” said a lead researcher participating in the report. “This gap is widening and poses a serious issue. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in electric power compared to overall mileage. They found that just a quarter of driving was done in EV mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, pollution amounts were well above lab projections. That occurred because electric motors were not strong sufficient to function independently, resulting to combustion motors using fossil fuels for almost one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled four large carmaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in running expenses than would be assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV cars are obviously far from the truth,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid vehicles have recently been brought again into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant car manufacturing.

Several senior politicians have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

One independent energy policy specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which segments of the car sector claimed there was insufficient data to accurately assess actual CO2 output.

“The results show, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “Any policy changes regarding PHEVs should be implemented with utmost care and considering this evidence.”