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Plug-in hybrid electric vehicles produce nearly five times greater global warming emissions than lab-reported figures indicate, according to a new analysis.

Widening Gap In Lab and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit group. This contrasts significantly with lab estimates, which assumed a 75% reduction in pollution.

Analysts studied information from onboard energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a lead researcher participating in the report. “This discrepancy is widening and poses a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric power relative to total mileage. They found that just a quarter of driving was completed in electric mode, whereas lab estimates assumed over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than lab projections. That happened because electric motors were insufficiently powerful enough to function independently, leading to engines burning gasoline for nearly a third of the travel covered in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four major automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra annually in operating expenses than is estimated under lab tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously way off the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from EU countries with significant automotive industries.

Several senior politicians have proposed PHEVs as a potential “compromise” option to include in the regulation.

One external energy policy specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, without question, that the difference between lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be made with extreme caution and in the light of that data.”