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Plug-in hybrid cars release almost five times greater global warming emissions than official figures indicate, as per a recent analysis.

Widening Gap Between Official and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel cars, according to research carried out by a non-profit group. That differs sharply with laboratory estimates, which suggested a three-quarters reduction in pollution.

Researchers studied data from onboard energy use monitors of 800,000 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 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a senior analyst participating in the study. “This gap is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery mode compared to total mileage. They determined that just 27% of travel was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were well above official projections. That occurred because EV motors were insufficiently powerful sufficient to operate alone, leading to combustion motors using gasoline for nearly one-third of the distance covered in electric mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV emissions allowed several large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 extra annually in operating costs than is estimated under lab tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly way off the truth,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little better than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been brought again into policy debates as automakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from member states with significant car industries.

Several senior officials have proposed PHEVs as a possible “flexibility” option to include in the legislation.

One independent energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which parts of the car industry claimed there was too little information to properly assess actual emissions.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”