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PHEVs emit almost five times more planet-heating emissions than lab-reported figures indicate, as per a new analysis.

Growing Discrepancy In Official and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a non-profit group. That contrasts sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers studied data from in-vehicle fuel consumption monitors of 800,000 cars registered in Europe from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a senior researcher involved in the report. “This gap is widening and poses a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to total mileage. The team found that just a quarter of travel was completed in electric mode, whereas lab estimates assumed 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab projections. That occurred because EV motors were insufficiently powerful enough to function alone, leading to engines using gasoline for almost a third of the distance completed in EV mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions allowed several major automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay about €500 more annually in operating expenses than is assumed under laboratory tests.

“The strong statements that automakers like to make about their PHEV cars are clearly far from the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought again into political debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and opposition from member states with large automotive industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the regulation.

One independent energy economics expert, who was unaffiliated with the research, called the report a “highly valuable contribution” after years in which parts of the car sector argued there was insufficient information to properly evaluate real-world CO2 output.

“These findings demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” they said. “All regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of this data.”