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PHEVs emit almost five times more global warming pollution than lab-reported figures indicate, as per a new analysis.

Widening Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, based on research conducted by a non-profit organization. This differs sharply with lab estimates, which assumed a 75% reduction in emissions.

Analysts studied data from onboard fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are falling,” said a lead researcher involved in the report. “This gap is growing and creates a significant problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in battery power relative to overall distance. The team determined that only a quarter of driving was done in EV mode, while official estimates assumed over four-fifths.

Even, when operating in EV mode, pollution levels were well above lab projections. This occurred because EV motors were not strong enough to operate alone, leading to combustion motors burning gasoline for almost a third of the travel covered in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV emissions enabled several large automaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 more annually in running costs than is estimated under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid cars have recently been brought again into policy debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant car manufacturing.

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

An independent energy economics expert, who was unaffiliated with the research, called the report a “highly valuable contribution” after years in which parts of the car industry claimed there was insufficient information to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert stated. “All regulatory changes regarding PHEVs should be implemented with extreme care and considering that evidence.”