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PHEVs release almost five times more global warming pollution than lab-reported data indicate, as per a new report.

Widening Gap In Official and Real-World Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, based on analysis conducted by a advocacy group. That contrasts significantly with lab estimates, which suggested a 75% reduction in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” stated a senior researcher participating in the report. “This gap is growing and creates a significant problem. As a result, PHEVs emit almost as heavily as gasoline cars.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in battery mode compared to overall distance. They determined that only a quarter of travel was done in electric mode, whereas lab estimates assumed 84%.

Additionally, when operating in electric mode, emission levels were significantly higher than official estimates. That occurred because electric motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using fossil fuels for almost one-third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions allowed four major carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 extra per year in operating costs than is assumed under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously way off the mark,” stated a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little better than regular petrol and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with significant automotive industries.

Some high-level politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after years in which segments of the car sector claimed there was too little data to accurately assess real-world CO2 output.

“These findings show, without question, that the gap in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they stated. “All policy changes regarding PHEVs should be implemented with extreme care and in the light of this evidence.”