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Plug-in hybrid electric vehicles produce nearly five times more global warming pollution than lab-reported figures show, according to a new report.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit organization. This differs significantly with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a senior analyst participating in the study. “This gap is widening and poses a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total distance. They found that only 27% of travel was done in electric mode, while official assumptions assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were well above official projections. That occurred because EV motors were not strong enough to function independently, leading to combustion motors using gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled several major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 extra per year in running costs than would be assumed under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Hybrid cars have lately been drawn again into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “compromise” option to include in the regulation.

One independent energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after years in which parts of the car sector argued there was too little information to properly evaluate real-world CO2 output.

“The results show, without question, that the gap in official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” the expert said. “All policy changes regarding PHEVs should be made with utmost care and considering that evidence.”