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Plug-in hybrid cars produce almost 5x more planet-heating pollution than official data show, as per a recent report.

Growing Discrepancy Between Lab and Real-World CO2 Output

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

Researchers examined information from onboard energy use meters of 800,000 vehicles registered in Europe from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “That gap is growing and poses a serious problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery mode relative to total distance. The team found that only a quarter of travel was completed in electric mode, while official estimates suggested over four-fifths.

Even, when running in EV mode, pollution amounts were well above official estimates. This occurred because EV motors were not strong enough to operate independently, resulting to combustion motors using fossil fuels for almost a third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several large automaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in operating costs than would be estimated under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought again into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from member states with large car manufacturing.

Several high-level politicians have suggested PHEVs as a potential “flexibility” option to introduce in the legislation.

An independent energy policy specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient information to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost care and considering that data.”