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Plug-in hybrid electric vehicles produce almost 5x more global warming emissions than official data indicate, as per a new report.

Growing Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy group. That differs significantly with lab estimates, which assumed a 75% decrease in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead researcher participating in the report. “This discrepancy is widening and poses a serious problem. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts linked most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total mileage. They found that just 27% of travel was done in electric mode, whereas official assumptions suggested 84%.

Even, when running in EV mode, emission levels were well above official projections. That occurred because EV motors were not strong sufficient to operate independently, resulting to combustion motors burning fossil fuels for nearly a third of the travel completed in EV mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major carmaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more annually in operating costs than is assumed under lab tests.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant automotive manufacturing.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

One external energy policy expert, who was unaffiliated with the research, described the report a “highly valuable addition” after years in which parts of the automotive sector claimed there was too little information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme caution and in the light of this data.”