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Plug-in hybrid electric vehicles emit nearly 5x more planet-heating emissions than official data indicate, as per a new report.

Growing Discrepancy In Official and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy organization. That contrasts significantly with laboratory tests, which assumed a three-quarters reduction in pollution.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 cars registered in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a lead researcher involved in the report. “That gap is widening and poses a serious issue. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power relative to overall mileage. The team found that just 27% of driving was done in electric mode, whereas official assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were well above official estimates. That happened because electric motors were insufficiently powerful sufficient to operate independently, leading to engines using gasoline for almost a third of the distance completed in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV emissions allowed several major automaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would pay about €500 extra annually in running costs than is assumed under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Hybrid vehicles have recently been brought again into political debates as automakers have pressed the EU to relax CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car industries.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

An independent energy economics specialist, who was not involved with the study, called the report a “highly valuable contribution” after years in which segments of the automotive industry claimed there was insufficient information to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the gap between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” they stated. “All regulatory changes regarding PHEVs should be made with extreme care and in the light of that evidence.”