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PHEVs emit almost five times more global warming pollution than lab-reported figures indicate, according to a new report.

Growing Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a non-profit group. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Researchers examined information from onboard fuel consumption monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a senior analyst involved in the study. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric mode relative to total distance. The team determined that just a quarter of travel was completed in electric mode, while official assumptions suggested 84%.

Even, when operating in EV mode, emission levels were significantly higher than official projections. That occurred because EV motors were not strong enough to operate independently, resulting to engines burning gasoline for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to estimates, the underestimation of PHEV emissions enabled several major automaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 extra per year in operating expenses than is assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV cars are clearly far from the truth,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Hybrid vehicles have recently been drawn again into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large automotive manufacturing.

Some senior officials have proposed PHEVs as a possible “flexibility” solution to include in the regulation.

An external energy economics specialist, who was unaffiliated with the study, called the report a “very useful contribution” after years in which parts of the car industry argued there was insufficient data to accurately evaluate real-world CO2 output.

“The results demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” they said. “All policy changes concerning PHEVs should be made with utmost care and in the light of this evidence.”