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PHEVs emit almost five times more global warming pollution than lab-reported data indicate, according to a new report.

Growing Gap Between Official and Real-World Emissions

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a non-profit group. That differs sharply with laboratory estimates, which suggested a three-quarters decrease in emissions.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” said a senior analyst involved in the report. “That gap is widening and creates a significant issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to overall mileage. They determined that only a quarter of travel was done in EV mode, while official assumptions suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than official projections. This occurred because EV motors were not strong sufficient to operate alone, leading to combustion motors burning gasoline for nearly one-third of the distance covered in electric mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed several large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in operating expenses than is estimated under lab tests.

“The strong statements that automakers like to make about their PHEV cars are clearly far from the mark,” commented a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from member states with large automotive manufacturing.

Several senior officials have proposed PHEVs as a possible “flexibility” option to include in the legislation.

One independent energy policy expert, who was unaffiliated with the research, called the report a “very useful contribution” after years in which segments of the car industry argued there was insufficient information to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” they said. “All regulatory changes concerning PHEVs should be made with utmost caution and considering that evidence.”