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Plug-in hybrid cars emit nearly five times more planet-heating emissions than official figures indicate, as per a new analysis.

Widening Discrepancy Between Official and Real-World Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit organization. This contrasts sharply with lab estimates, which assumed a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” said a senior analyst participating in the study. “That gap is growing and creates a serious issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to total distance. They found that just 27% of driving was completed in EV mode, while lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above official estimates. That occurred because EV motors were not strong sufficient to function alone, leading to combustion motors using fossil fuels for nearly a third of the travel covered in electric mode.

Policy and Economic Implications

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

Additionally, drivers of PHEVs would spend about €500 more annually in running costs than would be assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little better than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought again into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with significant automotive industries.

Some senior politicians have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after years in which segments of the automotive sector argued there was too little data to accurately evaluate real-world emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they stated. “All regulatory adjustments regarding PHEVs should be made with extreme care and in the light of that data.”