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PHEVs emit nearly five times greater planet-heating pollution than official data indicate, as per a new report.

Widening Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit organization. This contrasts sharply with lab tests, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead analyst participating in the report. “That gap is growing and poses a significant issue. As a result, PHEVs emit almost as much as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery power relative to total mileage. They determined that only 27% of travel was done in EV mode, while official assumptions assumed over four-fifths.

Even, when operating in EV mode, emission levels were well above official estimates. That occurred because EV motors were not strong sufficient to operate alone, leading to engines using fossil fuels for almost a third of the distance completed in EV mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several large carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more annually in operating costs than would be estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV cars are obviously far from the truth,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn again into political discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the car sector and opposition from EU countries with significant car industries.

Some high-level politicians have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

One external energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable addition” after a long period in which parts of the car sector argued there was insufficient information to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” they said. “Any policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of that data.”