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PHEVs emit nearly five times greater planet-heating pollution than official data show, according to a recent report.

Widening Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel vehicles, according to research carried out by a non-profit organization. That contrasts significantly with laboratory estimates, which assumed a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are falling,” stated a lead researcher participating in the report. “That gap is widening and creates a serious problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts linked most of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric power relative to total distance. They determined that only 27% of travel was done in EV mode, whereas official estimates suggested 84%.

Even, when running in electric mode, emission levels were well above lab projections. This happened because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning fossil fuels for almost a third of the travel covered in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled several major automaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more annually in operating expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been drawn back into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with significant car manufacturing.

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

An independent energy economics expert, who was unaffiliated with the research, called the analysis a “very useful addition” after a long period in which parts of the automotive sector claimed there was too little information to properly evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” they said. “All policy changes regarding PHEVs should be made with utmost care and considering this data.”