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Plug-in hybrid electric vehicles produce nearly 5x more global warming emissions than lab-reported figures show, as per a new analysis.

Widening Discrepancy In Official and Actual Emissions

Data shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. That differs sharply with lab tests, which suggested a three-quarters decrease in pollution.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a lead analyst involved in the study. “That gap is growing and poses a significant problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Factors Driving the Discrepancy

Researchers linked most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery power compared to overall distance. They found that just a quarter of driving was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were not strong sufficient to operate independently, resulting to engines using gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV emissions allowed several major automaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could pay approximately €500 more annually in running costs than is estimated under laboratory tests.

“The bold statements that manufacturers like to make about their PHEV cars are obviously way off the mark,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with large automotive industries.

Several high-level officials have suggested PHEVs as a possible “flexibility” option to include in the regulation.

One independent energy policy specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which parts of the automotive industry argued there was too little information to accurately assess actual CO2 output.

“These findings show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel cars,” the expert said. “Any policy adjustments concerning PHEVs should be made with utmost caution and considering that data.”