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Plug-in hybrid electric vehicles produce almost 5x greater global warming pollution than lab-reported data indicate, as per a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, according to analysis carried out by a non-profit organization. That differs significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts examined data from onboard energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are falling,” stated a senior researcher participating in the report. “That discrepancy is widening and creates a significant issue. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to overall distance. They determined that just a quarter of travel was completed in electric mode, whereas lab assumptions assumed 84%.

Even, when operating in EV mode, pollution levels were well above lab estimates. That occurred because electric motors were insufficiently powerful sufficient to operate independently, leading to engines burning gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled several major automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more annually in operating expenses than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been brought back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from member states with significant automotive manufacturing.

Some high-level politicians have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

One independent energy economics expert, who was not involved with the research, described the analysis a “very useful addition” after years in which segments of the car sector argued there was insufficient information to properly assess actual CO2 output.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and in the light of that data.”