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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than lab-reported data indicate, as per a recent analysis.

Widening Gap In Official and Real-World CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel cars, according to analysis conducted by a advocacy group. That contrasts sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts examined information from onboard fuel consumption meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead researcher involved in the study. “This gap is growing and poses a significant problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in electric mode compared to total distance. The team determined that only a quarter of driving was completed in EV mode, while official estimates assumed 84%.

Additionally, when running in EV mode, emission amounts were well above lab projections. This occurred because EV motors were not strong sufficient to function alone, leading to engines using gasoline for almost a third of the travel covered in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled four major automaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra annually in running expenses than would be estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with significant car manufacturing.

Some senior officials have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

An independent energy economics expert, who was unaffiliated with the study, called the analysis a “very useful addition” after years in which parts of the automotive industry argued there was too little data to accurately evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert said. “All policy adjustments regarding PHEVs should be implemented with utmost care and considering that data.”