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PHEVs release almost five times greater global warming pollution than lab-reported figures show, according to a new report.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. This differs significantly with laboratory tests, which suggested a three-quarters decrease in emissions.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand 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 lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a senior researcher participating in the report. “That discrepancy is growing and creates a significant issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total distance. The team found that only 27% of travel was done in EV mode, while official estimates assumed over four-fifths.

Even, when running in electric mode, emission levels were significantly higher than official projections. This happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using gasoline for nearly one-third of the travel completed in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more annually in operating costs than would be assumed under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into political discussions as carmakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with large automotive manufacturing.

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

One independent energy policy expert, who was not involved with the research, called the report a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient information to accurately assess actual emissions.

“The results demonstrate, without question, that the gap in lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and in the light of that evidence.”