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PHEVs release almost 5x greater planet-heating emissions than official figures show, according to a new report.

Widening Discrepancy Between Official and Real-World Emissions

Data reveals that PHEVs emit only 19% less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy organization. This differs significantly with lab tests, which suggested a 75% reduction in pollution.

Researchers studied information from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a lead analyst participating in the report. “This gap is widening and poses a significant problem. As a result, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode relative to overall distance. The team determined that just 27% of travel was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful enough to function alone, resulting to combustion motors using fossil fuels for nearly a third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV emissions enabled several large carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

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

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Political Debate and Automotive Lobbying

Hybrid vehicles have lately been brought back into policy discussions as automakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “compromise” solution to include in the regulation.

An external energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after a long period in which segments of the car industry argued there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be made with extreme caution and in the light of this evidence.”