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PHEVs produce almost five times more global warming pollution than official data indicate, as per a new report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy organization. That differs significantly with laboratory tests, which suggested a three-quarters decrease in emissions.

Researchers studied information from in-vehicle energy use meters of 800,000 vehicles registered in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” said a senior researcher participating in the study. “This discrepancy is widening and creates a serious issue. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery mode relative to total mileage. They determined that only 27% of driving was completed in electric mode, while official assumptions assumed 84%.

Even, when operating in electric mode, pollution levels were significantly higher than lab projections. This happened because EV motors were not strong sufficient to function independently, leading to engines using gasoline for nearly a third of the travel completed in electric mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled four large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more annually in running expenses than is assumed under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been brought again into political discussions as carmakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car industry and opposition from member states with significant car manufacturing.

Some senior officials have proposed PHEVs as a possible “compromise” solution to include in the regulation.

One independent energy economics expert, who was not involved with the study, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry argued there was too little information to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with extreme caution and in the light of this data.”