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Plug-in hybrid electric vehicles emit nearly five times greater global warming pollution than official data indicate, according to a recent report.

Growing Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a advocacy organization. This differs significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts studied information from onboard energy use monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. The team discovered 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 CO2 output are rising, while lab-reported figures are falling,” stated a senior analyst involved in the report. “This discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as much as petrol cars.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode relative to overall distance. They determined that just a quarter of driving was done in electric mode, while official assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than lab projections. That occurred because electric motors were not strong sufficient to function independently, leading to combustion motors burning gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions allowed four major carmaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more per year in running costs than is estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” commented a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have recently been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large car industries.

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

An external energy economics expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after a long period in which segments of the car sector argued there was insufficient information to properly evaluate actual CO2 output.

“These findings demonstrate, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they said. “All regulatory changes regarding PHEVs should be implemented with extreme care and in the light of that data.”