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PHEVs produce almost 5x greater global warming pollution than official data show, as per a recent analysis.

Widening Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs release just 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a non-profit organization. That differs sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” said a senior researcher participating in the study. “This discrepancy is widening and poses a significant issue. As a result, PHEVs pollute almost as much as petrol vehicles.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery mode relative to overall distance. The team determined that only 27% of driving was done in EV mode, whereas official assumptions suggested 84%.

Additionally, when operating in EV mode, pollution amounts were well above official estimates. That occurred because electric motors were not strong sufficient to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in EV mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed several large carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 extra annually in running expenses than is estimated under laboratory tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from member states with significant automotive industries.

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

One external energy policy expert, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the car sector argued there was insufficient data to accurately assess actual emissions.

“These findings demonstrate, without question, that the gap in official and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be made with utmost caution and in the light of that data.”