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PHEVs emit almost five times greater planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Widening Discrepancy In Official and Real-World Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than conventional petrol and diesel cars, according to research conducted by a non-profit organization. This contrasts sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts examined information from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a lead analyst participating in the study. “This gap is growing and creates a serious problem. As a result, PHEVs pollute almost as much as petrol cars.”

Primary Reasons Driving the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to overall mileage. The team found that only 27% of travel was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when operating in electric mode, emission amounts were significantly higher than official estimates. That occurred because electric motors were not strong enough to operate alone, leading to engines using gasoline for almost a third of the distance completed in electric mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV emissions enabled several major carmaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend about €500 more annually in operating costs than is assumed under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly way off 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 better than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been brought again into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with significant car industries.

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

An external energy economics specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient information to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with utmost care and in the light of that data.”