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Plug-in hybrid electric vehicles emit nearly 5x more global warming emissions than official data indicate, as per a recent report.

Growing Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit group. This differs sharply with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined information from onboard energy use monitors of 800,000 cars sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a senior analyst involved in the study. “This gap is growing and creates a significant problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in electric power compared to overall mileage. They determined that only a quarter of driving was done in electric mode, whereas lab estimates assumed 84%.

Additionally, when operating in electric mode, emission levels were significantly higher than official projections. This happened because electric motors were not strong sufficient to function alone, leading to combustion motors burning fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more annually in operating costs than is estimated under laboratory conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid cars have recently been brought again into political discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with large car manufacturing.

Some high-level officials have suggested plug-in hybrids as a potential “compromise” solution to include in the legislation.

An external energy economics expert, who was unaffiliated with the research, called the analysis a “very useful addition” after years in which parts of the car sector argued there was insufficient data to accurately assess real-world emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost care and considering that data.”