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Plug-in hybrid cars release nearly five times greater global warming pollution than official data indicate, as per a new report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit group. That differs sharply with lab estimates, which suggested a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a lead researcher participating in the study. “That discrepancy is growing and creates a serious problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Driving the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode compared to overall mileage. The team determined that just 27% of driving was completed in EV mode, while official assumptions assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above official estimates. That occurred because EV motors were not strong enough to function independently, resulting to engines burning gasoline for nearly a third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

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

“The strong claims that automakers often promote about their PHEV vehicles are obviously far from the truth,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into political discussions as carmakers have pressed the EU to relax CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with significant car manufacturing.

Some senior officials have proposed PHEVs as a potential “flexibility” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was insufficient data to properly assess real-world CO2 output.

“These findings show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be made with utmost caution and considering this data.”