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PHEVs emit nearly 5x greater planet-heating pollution than official data show, according to a new analysis.

Widening Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit group. This differs sharply with lab estimates, which suggested a three-quarters reduction in pollution.

Analysts examined data from onboard fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst involved in the report. “That gap is widening and creates a significant problem. As a result, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery mode compared to overall distance. They determined that only 27% of driving was completed in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in EV mode, emission levels were significantly higher than lab estimates. This occurred because EV motors were not strong enough to function alone, leading to combustion motors burning fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions allowed several major automaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in running expenses than would be assumed under lab tests.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car industry and resistance from member states with large car industries.

Some senior politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the regulation.

An external energy economics expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after years in which segments of the car industry argued there was too little information to properly evaluate actual emissions.

“The results show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional vehicles,” they stated. “All regulatory changes regarding PHEVs should be implemented with extreme caution and considering this data.”