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Plug-in hybrid cars produce almost 5x more global warming pollution than lab-reported figures indicate, as per a new analysis.

Widening Discrepancy In Official and Real-World Emissions

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a advocacy organization. This differs sharply with lab estimates, which suggested a three-quarters reduction in pollution.

Researchers examined data from onboard energy use meters of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a senior researcher participating in the report. “That discrepancy is growing and poses a serious issue. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery mode compared to overall distance. The team found that just 27% of travel was done in electric mode, whereas official estimates assumed over four-fifths.

Even, when running in EV mode, emission levels were well above lab projections. That occurred because EV motors were insufficiently powerful enough to operate independently, leading to engines burning fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several major carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The bold claims that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into policy discussions as automakers have lobbied the EU to relax CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

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

An independent energy policy expert, who was not involved with the research, described the report a “highly valuable addition” after years in which parts of the car sector argued there was too little data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of that data.”