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Plug-in hybrid cars produce almost 5x more planet-heating emissions than official figures indicate, according to a recent report.

Growing Gap In Official and Actual CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than conventional petrol and diesel cars, according to analysis conducted by a advocacy group. That differs sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers studied information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” stated a lead researcher participating in the study. “This gap is growing and creates a serious problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to total mileage. The team found that just a quarter of driving was completed in EV mode, while lab estimates assumed over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than official estimates. That occurred because electric motors were not strong sufficient to operate independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

Based on estimates, the lowballing of PHEV emissions allowed four major automaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in running expenses than is estimated under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought again into policy debates as automakers have pressed the European Union to relax CO₂ standards. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with significant automotive manufacturing.

Some senior officials have suggested PHEVs as a potential “flexibility” option to include in the regulation.

An independent energy policy expert, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little data to properly assess actual emissions.

“The results show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” the expert stated. “All policy adjustments regarding PHEVs should be made with extreme caution and considering this data.”