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PHEVs emit almost 5x more global warming emissions than lab-reported figures indicate, according to a new report.

Widening Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, according to research conducted by a non-profit organization. That differs sharply with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers examined information from onboard energy use monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “This gap is growing and poses a serious issue. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to overall mileage. The team determined that just a quarter of travel was completed in EV mode, while lab assumptions suggested 84%.

Even, when running in electric mode, emission amounts were well above official estimates. That occurred because electric motors were insufficiently powerful enough to function alone, resulting to combustion motors using gasoline for almost a third of the travel covered in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV emissions allowed four major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra annually in running expenses than is estimated under laboratory tests.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Debate and Industry Lobbying

Hybrid vehicles have lately been brought again into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large automotive manufacturing.

Several high-level officials have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

One independent energy policy specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little information to properly evaluate actual emissions.

“The results show, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with extreme care and considering that evidence.”