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PHEVs release nearly five times greater planet-heating pollution than official figures indicate, as per a new report.

Growing Gap In Lab and Real-World Emissions

Statistics shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, according to research conducted by a non-profit group. That differs significantly with laboratory tests, which suggested a three-quarters decrease in pollution.

Analysts examined information from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” said a lead analyst participating in the study. “That gap is widening and creates a serious problem. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Behind the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power compared to overall distance. They found that only 27% of travel was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Even, when running in electric mode, emission amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful sufficient to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several major carmaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more annually in operating costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little better than standard petrol and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from member states with large automotive industries.

Several high-level politicians have proposed PHEVs as a potential “flexibility” solution to include in the regulation.

One independent energy policy expert, who was not involved with the study, described the analysis a “very useful addition” after years in which parts of the car industry claimed there was insufficient information to accurately evaluate actual emissions.

“The results show, without question, that the gap in official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with utmost care and in the light of this data.”