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Plug-in hybrid electric vehicles produce almost 5x more global warming emissions than official data indicate, according to a recent analysis.

Widening Discrepancy In Official and Real-World CO2 Output

Data reveals that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, according to research conducted by a non-profit organization. This contrasts significantly with lab estimates, which suggested a 75% decrease in pollution.

Analysts studied data from onboard energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a lead analyst participating in the study. “This gap is widening and poses a serious problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in battery power relative to total distance. They found that just 27% of travel was completed in EV mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, pollution amounts were significantly higher than official estimates. This occurred because electric motors were insufficiently powerful enough to function alone, leading to combustion motors burning gasoline for almost one-third of the distance covered in electric mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output allowed several major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in operating costs than is assumed under lab tests.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into political debates as automakers have pressed the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from EU countries with significant automotive manufacturing.

Several high-level officials have suggested PHEVs as a possible “compromise” option to introduce in the legislation.

One external energy economics specialist, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which segments of the automotive industry argued there was too little information to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or conventional cars,” the expert stated. “Any regulatory changes concerning PHEVs should be made with extreme caution and in the light of that evidence.”