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Plug-in hybrid electric vehicles produce almost five times greater global warming pollution than lab-reported figures indicate, according to a recent analysis.

Growing Gap In Lab and Actual Emissions

Data shows that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy organization. That differs sharply with lab tests, which assumed a 75% reduction in pollution.

Researchers studied information from in-vehicle fuel consumption meters of eight hundred thousand cars registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a lead analyst involved in the report. “This gap is growing and poses a serious problem. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to overall distance. They determined that just 27% of travel was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission levels were well above lab projections. That occurred because EV motors were not strong sufficient to function independently, leading to engines using fossil fuels for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV emissions allowed several major automaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in running expenses than is estimated under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have recently been brought again into policy discussions as carmakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An external energy policy specialist, who was not involved with the study, called the analysis a “very useful contribution” after years in which segments of the automotive industry claimed there was too little information to properly assess actual emissions.

“The results show, without question, that the difference in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert said. “Any policy changes regarding PHEVs should be made with utmost care and in the light of this evidence.”