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Plug-in hybrid electric vehicles emit almost five times greater planet-heating pollution than official figures indicate, as per a recent analysis.

Widening Gap Between Lab and Real-World Emissions

Data shows that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel cars, according to research conducted by a non-profit group. This contrasts significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are falling,” stated a senior researcher involved in the report. “This discrepancy is growing and poses a serious problem. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of miles driven in electric mode compared to overall mileage. The team found that just a quarter of driving was done in EV mode, while lab assumptions assumed 84%.

Even, when running in electric mode, emission levels were well above official estimates. That occurred because EV motors were insufficiently powerful enough to function alone, resulting to combustion motors using gasoline for nearly a third of the travel completed in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output allowed four major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 extra per year in operating costs than would be estimated under laboratory conditions.

“The bold claims that manufacturers like to make about their PHEV cars are obviously far from the truth,” commented a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been brought back into political discussions as carmakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with large automotive manufacturing.

Some high-level officials have suggested PHEVs as a potential “flexibility” option to include in the legislation.

An independent energy policy expert, who was not involved with the study, called the analysis a “very useful contribution” after years in which parts of the automotive sector claimed there was insufficient data to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost caution and in the light of that evidence.”