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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating emissions than lab-reported figures indicate, according to a new report.

Growing Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy group. This contrasts sharply with lab tests, which assumed a 75% decrease in emissions.

Analysts examined information from onboard energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a senior researcher involved in the report. “This gap is growing and creates a serious problem. As a result, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to overall distance. The team found that only a quarter of driving was done in electric mode, while lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission amounts were well above official projections. This occurred because EV motors were not strong sufficient to operate independently, leading to engines using gasoline for nearly a third of the distance covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV emissions enabled four major automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 extra per year in operating expenses than would be assumed under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been brought again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with significant car manufacturing.

Some high-level officials have proposed PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy policy expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was insufficient information to accurately assess actual 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 gasoline or diesel cars,” the expert said. “Any policy adjustments concerning PHEVs should be made with extreme caution and in the light of that evidence.”