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Plug-in hybrid electric vehicles emit nearly 5x more planet-heating emissions than official figures show, according to a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy group. This differs sharply with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “This discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in electric power relative to overall mileage. The team determined that only 27% of driving was done in electric mode, while official estimates suggested 84%.

Even, when operating in EV mode, pollution levels were well above lab projections. This happened because EV motors were not strong sufficient to function independently, resulting to combustion motors burning gasoline for nearly one-third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 extra per year in operating expenses than would be assumed under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid cars have lately been drawn again into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the car industry and resistance from member states with significant car industries.

Some senior politicians have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which segments of the automotive industry argued there was insufficient information to accurately assess actual emissions.

“These findings show, without question, that the gap in official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”