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PHEVs produce almost five times greater planet-heating emissions than official data indicate, according to a recent report.

Widening Gap Between Official and Actual Emissions

Statistics shows that PHEVs release only 19% less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. That contrasts sharply with lab estimates, which assumed a 75% reduction in emissions.

Researchers studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” said a senior researcher participating in the study. “That discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in electric mode relative to total mileage. The team found that just 27% of travel was completed in EV mode, while lab estimates suggested over four-fifths.

Even, when operating in electric mode, emission amounts were well above official estimates. This happened because EV motors were not strong sufficient to operate independently, resulting to engines burning gasoline for almost one-third of the distance covered in EV mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed several large carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 more annually in operating expenses than would be assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Automotive Lobbying

Hybrid vehicles have recently been brought again into political debates as automakers have pressed the EU to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with significant car industries.

Some high-level officials have proposed plug-in hybrids as a potential “flexibility” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the study, described the report a “very useful addition” after years in which parts of the automotive industry argued there was insufficient information to properly evaluate real-world emissions.

“The results show, without question, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they stated. “All regulatory changes regarding PHEVs should be made with utmost care and in the light of that evidence.”