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Plug-in hybrid cars produce almost five times more planet-heating pollution than official figures indicate, as per a recent analysis.

Widening Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy group. That contrasts significantly with lab tests, which assumed a three-quarters decrease in emissions.

Researchers examined data from in-vehicle energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and poses a serious issue. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery mode relative to total distance. They determined that just a quarter of travel was done in electric mode, whereas lab assumptions assumed 84%.

Additionally, when operating in electric mode, emission levels were significantly higher than official estimates. This occurred because electric motors were not strong enough to function independently, leading to combustion motors burning fossil fuels for almost a third of the travel covered in EV mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV emissions enabled four large automaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more annually in running costs than would be estimated under lab conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from EU countries with large car manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An external energy economics expert, who was not involved with the research, called the report a “highly valuable contribution” after years in which segments of the automotive industry argued there was too little data to properly evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they stated. “Any policy changes regarding PHEVs should be made with extreme care and in the light of this data.”