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Plug-in hybrid cars release almost 5x greater global warming pollution than official figures show, as per a recent report.

Widening Discrepancy In Lab and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy group. That differs significantly with lab tests, which suggested a 75% decrease in emissions.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a lead researcher participating in the study. “This discrepancy is widening and poses a serious problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode relative to overall distance. They found that only a quarter of driving was done in electric mode, while official assumptions assumed 84%.

Even, when running in electric mode, emission levels were significantly higher than official projections. That happened because EV motors were not strong sufficient to operate alone, resulting to combustion motors burning fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed four major carmaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra annually in operating costs than is assumed under laboratory tests.

“The strong statements that automakers like to make about their PHEV vehicles are obviously far from the mark,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with significant car industries.

Several high-level officials have proposed PHEVs as a possible “flexibility” option to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the car sector claimed there was too little information to accurately assess actual emissions.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert said. “Any regulatory changes concerning PHEVs should be made with extreme caution and considering this evidence.”