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Plug-in hybrid electric vehicles release almost five times greater global warming pollution than lab-reported figures indicate, as per a recent report.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a advocacy organization. This differs sharply with laboratory tests, which assumed a 75% reduction in pollution.

Researchers studied information from in-vehicle fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a lead researcher involved in the study. “This gap is widening and poses a serious issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total distance. They determined that just a quarter of travel was completed in electric mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, emission levels were well above official estimates. This occurred because EV motors were not strong sufficient to operate independently, leading to combustion motors burning fossil fuels for almost a third of the travel covered in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed several large automaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could pay about €500 more annually in operating costs than is estimated under laboratory tests.

“The strong statements that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An external energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after years in which parts of the automotive sector argued there was too little information to properly evaluate real-world CO2 output.

“These findings show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel cars,” they stated. “Any policy changes regarding PHEVs should be implemented with extreme care and in the light of this evidence.”