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Plug-in hybrid cars produce nearly 5x more global warming pollution than official figures indicate, according to a recent analysis.

Growing Gap Between Official and Real-World Emissions

Statistics shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy organization. That differs sharply with laboratory estimates, which assumed a three-quarters reduction in pollution.

Analysts examined data from onboard energy use meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” said a lead researcher participating in the study. “This gap is growing and creates a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power compared to overall mileage. They determined that only a quarter of travel was completed in EV mode, while lab assumptions suggested 84%.

Even, when operating in EV mode, emission levels were significantly higher than official projections. That occurred because electric motors were not strong enough to operate alone, resulting to combustion motors using gasoline for almost a third of the travel covered in EV mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four major carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 extra annually in operating expenses than would be assumed under lab tests.

“The strong statements that automakers often promote about their PHEV vehicles are clearly far from the mark,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from member states with large car manufacturing.

Some senior politicians have suggested PHEVs as a potential “compromise” option to include in the legislation.

One external energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after years in which parts of the car sector argued there was too little information to properly assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be made with extreme caution and considering this evidence.”