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PHEVs produce nearly five times greater planet-heating emissions than official figures indicate, as per a new analysis.

Widening Gap Between Official and Actual Emissions

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit organization. That contrasts significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 cars sold in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a senior analyst participating in the report. “That gap is growing and creates a serious issue. As a result, PHEVs pollute nearly as much as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total distance. The team found that just a quarter of driving was done in EV mode, while official estimates assumed 84%.

Even, when running in EV mode, pollution levels were significantly higher than official projections. This occurred because EV motors were not strong sufficient to function alone, leading to combustion motors burning gasoline for nearly a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV emissions allowed several large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 more per year in running costs than is assumed under laboratory tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are obviously way off the truth,” stated a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been drawn back into political discussions as automakers have lobbied the European Union to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with significant automotive industries.

Some high-level politicians have suggested PHEVs as a potential “flexibility” solution to include in the legislation.

An independent energy policy specialist, who was not involved with the research, described the analysis a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little information to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “Any regulatory changes concerning PHEVs should be made with utmost care and in the light of this evidence.”