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Plug-in hybrid electric vehicles emit almost five times greater planet-heating pollution than lab-reported figures indicate, as per a new analysis.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy group. This contrasts sharply with laboratory tests, which suggested a three-quarters decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a senior researcher involved in the study. “That gap is growing and creates a serious issue. As a result, PHEVs pollute almost as much as gasoline 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 battery power compared to total mileage. The team found that only 27% of driving was completed in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were well above 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 distance covered in electric mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output enabled several major carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 extra per year in running costs than would be assumed under lab tests.

“The strong statements that automakers like to make about their PHEV cars are obviously far from the truth,” stated a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Hybrid vehicles have recently been drawn again into political discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant automotive industries.

Several senior officials have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

An external energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after years in which segments of the automotive industry claimed there was insufficient data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel vehicles,” they said. “All policy changes regarding PHEVs should be implemented with utmost caution and in the light of this data.”