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PHEVs release nearly 5x more global warming emissions than official figures indicate, according to a new analysis.

Growing Gap In Official and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit group. That differs sharply with lab tests, which assumed a three-quarters decrease in pollution.

Analysts studied information from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a senior researcher involved in the study. “This discrepancy is widening and creates a serious problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power relative to overall mileage. The team found that just 27% of driving was done in EV mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, emission amounts were well above official projections. That happened because electric motors were insufficiently powerful sufficient to function alone, resulting to combustion motors using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several major automaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 more annually in operating expenses than is estimated under lab tests.

“The bold statements that automakers like to make about their PHEV vehicles are obviously way off the truth,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Political Debate and Automotive Lobbying

Hybrid cars have lately been brought back into policy debates as carmakers have lobbied the EU to relax CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and resistance from EU countries with large car industries.

Several high-level officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An independent energy policy specialist, who was not involved with the research, called the report a “very useful addition” after years in which parts of the car industry claimed there was too little data to properly assess actual emissions.

“The results demonstrate, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and considering this evidence.”