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PHEVs produce nearly five times more global warming pollution than official data indicate, as per a new analysis.

Growing Gap Between Official and Actual Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. This differs significantly with laboratory estimates, which assumed a 75% reduction in emissions.

Researchers examined information from in-vehicle fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior analyst participating in the study. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode relative to overall distance. They found that only a quarter of driving was completed in electric mode, whereas official estimates assumed 84%.

Additionally, when operating in electric mode, emission amounts were well above official estimates. That happened because EV motors were not strong enough to operate alone, leading to engines using fossil fuels for nearly one-third of the distance covered in electric mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions enabled four large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay about €500 extra per year in operating costs than is estimated under laboratory conditions.

“The strong claims that automakers often promote about their PHEV vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn back into policy debates as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive manufacturing.

Some high-level officials have proposed PHEVs as a possible “compromise” option to include in the legislation.

An independent energy policy expert, who was not involved with the research, described the report a “very useful addition” after a long period in which segments of the automotive sector claimed there was too little information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” the expert said. “Any policy changes concerning PHEVs should be made with extreme caution and considering that data.”