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Plug-in hybrid electric vehicles produce almost five times more global warming pollution than official figures indicate, according to a new analysis.

Growing Gap In Official and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy organization. That contrasts sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts examined information from onboard energy use meters of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead analyst involved in the report. “That gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Analysts linked most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery power relative to total distance. They determined that just a quarter of driving was done in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when running in EV mode, pollution levels were significantly higher than official estimates. That occurred because EV motors were insufficiently powerful enough to function alone, leading to engines burning fossil fuels for nearly a third of the travel completed in electric mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed several large automaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in running expenses than is assumed under lab conditions.

“The bold claims that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn back into political debates as automakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with significant automotive manufacturing.

Several senior politicians have suggested PHEVs as a possible “flexibility” solution to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which parts of the car sector claimed there was insufficient information to properly assess actual emissions.

“These findings show, beyond any doubt, that the gap in official and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel cars,” they stated. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of this evidence.”