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PHEVs release nearly five times greater planet-heating emissions than lab-reported figures indicate, according to a new report.

Widening Gap In Lab and Real-World Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy organization. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” stated a lead researcher participating in the report. “That gap is growing and poses a significant issue. As a result, PHEVs emit almost as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to overall distance. The team determined that only a quarter of driving was completed in EV mode, while lab estimates assumed over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. That occurred because EV motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed several large carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 extra annually in running costs than would be estimated under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have recently been drawn back into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and resistance from EU countries with large car industries.

Several senior officials have suggested plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which parts of the automotive industry argued there was too little information to properly assess real-world emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel vehicles,” the expert said. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and in the light of this evidence.”