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PHEVs produce nearly five times greater planet-heating emissions than official figures show, as per a recent analysis.

Growing Gap Between Lab and Actual Emissions

Statistics shows that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit group. That differs sharply with lab estimates, which assumed a three-quarters decrease in pollution.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a senior analyst participating in the report. “This gap is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery mode compared to overall mileage. The team determined that only 27% of driving was done in EV mode, whereas lab estimates suggested 84%.

Additionally, when operating in electric mode, pollution amounts were well above lab projections. That occurred because EV motors were not strong sufficient to operate alone, leading to engines burning fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed four major automaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 extra annually in operating expenses than is assumed under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with large automotive manufacturing.

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

An independent energy economics specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which parts of the car industry claimed there was too little data to properly evaluate actual CO2 output.

“The results show, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” they said. “Any regulatory changes regarding PHEVs should be made with utmost care and in the light of that evidence.”