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PHEVs emit almost five times more global warming emissions than lab-reported data indicate, as per a new report.

Growing Gap Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit organization. That contrasts sharply with lab tests, which suggested a 75% decrease in pollution.

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

“Actual CO2 output are rising, while official figures are falling,” stated a lead researcher involved in the study. “That discrepancy is widening and creates a serious problem. As a result, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery power relative to overall mileage. They found that only 27% of travel was completed in electric mode, while lab estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution levels were significantly higher than official estimates. That happened because EV motors were insufficiently powerful sufficient to function alone, resulting to engines burning gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Economic Consequences

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

Additionally, owners of PHEVs would spend approximately €500 extra annually in running expenses than would be estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy debates as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car industry and resistance from member states with significant automotive manufacturing.

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

One independent energy policy expert, who was not involved with the research, described the report a “highly valuable addition” after a long period in which parts of the car industry claimed there was insufficient data to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel cars,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme care and considering this evidence.”