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Plug-in hybrid electric vehicles release nearly 5x more global warming emissions than lab-reported data indicate, as per a new analysis.

Growing Gap In Official and Actual Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy group. This differs significantly with lab tests, which suggested a three-quarters decrease in pollution.

Analysts examined information from onboard energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a lead researcher involved in the study. “That gap is growing and poses a serious issue. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power relative to overall mileage. The team determined that just 27% of driving was completed in electric mode, while lab estimates suggested 84%.

Even, when running in EV mode, pollution levels were significantly higher than lab estimates. This occurred because electric motors were not strong sufficient to operate independently, leading to combustion motors using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV emissions allowed several large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in operating expenses than is estimated under lab tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly way off the mark,” stated a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with large car manufacturing.

Several high-level politicians have suggested PHEVs as a possible “compromise” option to include in the legislation.

An external energy economics expert, who was unaffiliated with the study, called the report a “very useful contribution” after a long period in which parts of the automotive industry argued there was too little information to accurately assess real-world emissions.

“The results show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” they said. “Any policy changes regarding PHEVs should be made with utmost caution and in the light of this data.”