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PHEVs release nearly 5x more global warming pollution than official data indicate, as per a new analysis.

Growing Gap In Official and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than conventional gas and diesel vehicles, according to research carried out by a advocacy organization. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in emissions.

Researchers studied data from onboard fuel consumption meters of 800,000 vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a lead analyst involved in the study. “That gap is growing and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Factors Behind the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in electric power relative to total mileage. The team found that only 27% of driving was done in EV mode, while official estimates suggested 84%.

Additionally, when running in electric mode, pollution levels were well above official projections. This happened because electric motors were insufficiently powerful enough to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Consequences

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

Furthermore, owners of PHEVs could pay about €500 extra per year in operating costs than is estimated under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn again into political discussions as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with significant car manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “compromise” option to include in the regulation.

One external energy economics expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after years in which segments of the automotive industry claimed there was insufficient data to properly evaluate actual emissions.

“The results demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or diesel vehicles,” they said. “Any policy adjustments regarding PHEVs should be made with utmost care and considering this data.”