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Plug-in hybrid cars release nearly five times more planet-heating emissions than official figures indicate, as per a new report.

Growing Gap Between Official and Real-World Emissions

Data shows that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel vehicles, according to research carried out by a non-profit organization. This differs sharply with lab estimates, which suggested a 75% reduction in emissions.

Researchers examined information from in-vehicle energy use meters of 800,000 cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a senior analyst participating in the study. “This gap is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in electric mode relative to total distance. The team determined that only 27% of travel was completed in electric mode, while official estimates assumed 84%.

Even, when running in EV mode, pollution levels were well above lab projections. This happened because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled several large carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 extra per year in operating costs than is estimated under laboratory conditions.

“The bold statements that automakers like to make about their PHEV cars are clearly far from the mark,” commented a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been drawn back into political discussions as automakers have lobbied the EU to relax CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large automotive manufacturing.

Several senior officials have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

An independent energy economics expert, who was unaffiliated with the research, called the report a “very useful contribution” after a long period in which parts of the car sector claimed there was insufficient information to properly evaluate real-world emissions.

“These findings show, without question, that the difference in official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel cars,” they stated. “Any policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of this evidence.”