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Plug-in hybrid electric vehicles release nearly five times greater global warming pollution than official figures indicate, according to a new report.

Growing Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs release just one-fifth less CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy organization. This differs significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts examined information from in-vehicle energy use meters of 800,000 cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a senior researcher involved in the study. “That discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to total distance. They determined that just 27% of travel was completed in EV mode, whereas official estimates assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. That occurred because electric motors were not strong enough to function independently, resulting to combustion motors burning fossil fuels for nearly a third of the travel covered in electric mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major automaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend about €500 more annually in operating expenses than would be estimated under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn again into political debates as automakers have pressed the European Union to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and resistance from EU countries with large car industries.

Several high-level politicians have proposed PHEVs as a possible “compromise” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, called the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little data to properly evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with extreme care and considering that evidence.”