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PHEVs release nearly five times more global warming emissions than official data show, according to a new analysis.

Growing Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy group. That contrasts significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a lead researcher participating in the study. “That gap is growing and creates a serious problem. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the difference to overestimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total distance. They determined that just a quarter of driving was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official projections. That occurred because electric motors were not strong sufficient to operate alone, leading to engines burning gasoline for nearly a third of the distance completed in electric mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend about €500 more annually in operating costs than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into policy debates as automakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from member states with significant car manufacturing.

Some senior politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

One independent energy economics specialist, who was unaffiliated with the research, described the analysis a “very useful addition” after years in which segments of the automotive industry argued there was too little information to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they stated. “Any policy adjustments regarding PHEVs should be made with utmost care and considering that data.”