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Plug-in hybrid cars produce almost five times greater global warming emissions than official figures indicate, as per a new report.

Growing Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. This contrasts sharply with lab tests, which suggested a three-quarters reduction in pollution.

Analysts studied data from onboard energy use meters of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a lead researcher involved in the study. “That discrepancy is widening and poses a serious problem. As a result, PHEVs emit almost as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery power relative to overall distance. They determined that just 27% of travel was completed in EV mode, while official assumptions assumed 84%.

Additionally, when running in electric mode, pollution amounts were well above official projections. This occurred because EV motors were not strong sufficient to function independently, leading to combustion motors using gasoline for almost a third of the travel completed in electric mode.

Regulatory and Economic Consequences

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

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in operating expenses than would be assumed under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little better than standard gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large automotive industries.

Some senior officials have proposed plug-in hybrids as a potential “compromise” solution to include in the legislation.

One external energy policy specialist, who was not involved with the research, described the analysis a “very useful addition” after a long period in which segments of the car sector claimed there was insufficient information to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional cars,” the expert stated. “All regulatory changes regarding PHEVs should be made with extreme caution and considering this data.”