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Plug-in hybrid electric vehicles release nearly five times greater global warming emissions than official data show, according to a new analysis.

Widening Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy organization. That contrasts significantly with laboratory tests, which assumed a three-quarters reduction in pollution.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior analyst participating in the study. “That gap is growing and poses a serious problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power compared to total distance. The team found that only 27% of driving was completed in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were significantly higher than official estimates. That happened because EV motors were insufficiently powerful enough to operate alone, leading to engines using gasoline for nearly a third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output enabled several major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 extra per year in operating expenses than is assumed under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Pressure

Hybrid cars have lately been brought again into political debates as automakers have pressed the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant automotive manufacturing.

Several high-level politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An external energy economics expert, who was unaffiliated with the research, described the analysis a “very useful addition” after a long period in which parts of the automotive industry argued there was insufficient information to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” they stated. “Any policy changes concerning PHEVs should be implemented with extreme care and considering that evidence.”