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PHEVs emit almost five times greater planet-heating emissions than lab-reported data show, as per a new analysis.

Widening Gap Between Lab and Actual Emissions

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy organization. That contrasts sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a lead analyst involved in the report. “That discrepancy is growing and poses a significant issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to total mileage. The team found that only 27% of driving was done in EV mode, while official estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were well above lab estimates. That occurred because EV motors were not strong sufficient to operate alone, leading to combustion motors burning gasoline for nearly a third of the distance covered in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more per year in operating costs than would be assumed under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Pressure

Hybrid vehicles have lately been drawn again into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant car manufacturing.

Several high-level politicians have suggested PHEVs as a possible “compromise” solution to include in the regulation.

An external energy policy expert, who was unaffiliated with the research, called the report a “very useful contribution” after years in which parts of the car industry claimed there was too little information to accurately evaluate real-world CO2 output.

“These findings show, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” the expert stated. “All policy adjustments regarding PHEVs should be made with extreme caution and considering that data.”