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PHEVs release nearly 5x greater planet-heating pollution than lab-reported data show, as per a new analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a non-profit organization. That differs sharply with lab estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” stated a senior researcher participating in the study. “This discrepancy is growing and creates a serious problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery mode compared to total mileage. They found that just 27% of travel was done in EV mode, whereas official estimates assumed 84%.

Additionally, when operating in electric mode, emission levels were well above official estimates. This happened because EV motors were not strong sufficient to function alone, resulting to engines burning gasoline for nearly a third of the travel completed in electric mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more annually in running expenses than is assumed under laboratory conditions.

“The bold statements that automakers often promote about their PHEV cars are obviously way off the truth,” stated a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

Hybrid cars have lately been brought again into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large car manufacturing.

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

An external energy economics expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which parts of the car sector claimed there was insufficient data to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional vehicles,” the expert said. “Any regulatory changes regarding PHEVs should be implemented with utmost care and in the light of that evidence.”