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Plug-in hybrid cars produce nearly 5x more global warming pollution than lab-reported figures show, according to a recent report.

Growing Discrepancy Between Official and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy organization. That contrasts sharply with laboratory estimates, which assumed a 75% decrease in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” said a lead analyst involved in the study. “This discrepancy is growing and poses a serious problem. As a result, PHEVs emit almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery mode compared to overall mileage. The team determined that only 27% of travel was completed in EV mode, while official estimates assumed 84%.

Additionally, when operating in electric mode, pollution amounts were well above lab projections. That occurred because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV emissions allowed four major automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more annually in running costs than is estimated under lab tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have lately been brought back into political discussions as carmakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant car manufacturing.

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

An independent energy policy expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the car sector claimed there was insufficient data to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the gap between official and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional cars,” they stated. “All policy changes concerning PHEVs should be made with utmost care and in the light of that evidence.”