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

Growing Gap Between Official and Actual Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel cars, based on research carried out by a non-profit organization. This differs sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts examined information from in-vehicle fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a senior researcher participating in the study. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to total mileage. The team found that just a quarter of travel was completed in EV mode, whereas lab assumptions assumed 84%.

Even, when operating in electric mode, pollution amounts were well above official estimates. That occurred because EV motors were insufficiently powerful enough to operate alone, leading to engines burning gasoline for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled four large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating expenses than would be assumed under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into policy discussions as carmakers have pressed the European Union to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and opposition from EU countries with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

An independent energy policy expert, who was not involved with the research, described the report a “highly valuable contribution” after a long period in which segments of the car sector claimed there was insufficient information to accurately evaluate actual emissions.

“These findings show, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme caution and in the light of that data.”