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Plug-in hybrid electric vehicles emit almost 5x more global warming pollution than official figures indicate, as per a new analysis.

Growing Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit group. That differs significantly with lab tests, which suggested a three-quarters reduction in emissions.

Analysts examined information from in-vehicle energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” stated a senior analyst participating in the study. “That gap is widening and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery mode compared to overall mileage. The team determined that only a quarter of travel was completed in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution levels were significantly higher than official projections. That occurred because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV emissions enabled several large automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 extra per year in operating costs than would be assumed under laboratory tests.

“The bold claims that automakers like to make about their PHEV cars are clearly far from the mark,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

Hybrid vehicles have lately been drawn back into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant automotive industries.

Several senior officials have proposed PHEVs as a potential “compromise” solution to include in the legislation.

One independent energy policy specialist, who was not involved with the study, described the analysis a “very useful addition” after years in which segments of the automotive industry argued there was too little information to properly evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional vehicles,” they said. “Any regulatory changes regarding PHEVs should be implemented with utmost care and considering this data.”