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PHEVs produce nearly five times greater planet-heating pollution than lab-reported data indicate, according to a recent report.

Growing Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, based on analysis carried out by a non-profit organization. This contrasts sharply with laboratory tests, which assumed a three-quarters reduction in emissions.

Researchers studied data from onboard energy use meters of 800,000 vehicles 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 estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead researcher participating in the study. “That gap is growing and creates a serious issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Factors Behind the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of miles driven in electric power compared to overall distance. They determined that just a quarter of travel was completed in EV mode, whereas official assumptions suggested 84%.

Even, when running in electric mode, emission amounts were well above lab estimates. This happened because electric motors were not strong enough to function independently, leading to engines burning gasoline for almost a third of the distance covered in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions allowed several major automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more per year in running costs than is estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV cars are clearly far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been drawn back into political discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with significant automotive industries.

Some senior officials have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

An independent energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which segments of the automotive sector claimed there was too little information to accurately assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert said. “Any policy adjustments regarding PHEVs should be made with extreme care and considering that data.”