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Plug-in hybrid electric vehicles release almost 5x greater global warming emissions than official data indicate, as per a new report.

Growing Gap In Official and Actual Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a non-profit group. That contrasts significantly with lab estimates, which suggested a 75% decrease in emissions.

Researchers examined information from onboard energy use meters of 800,000 cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead analyst involved in the study. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in battery power compared to overall mileage. They found that only a quarter of travel was done in EV mode, while official estimates assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official estimates. That happened because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors burning gasoline for nearly a third of the travel completed in electric mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled several major carmaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more per year in running costs than is estimated under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a transport expert. “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 standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been brought again into political discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with significant automotive industries.

Several senior politicians have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

One independent energy economics specialist, who was not involved with the study, described the analysis a “highly valuable addition” after a long period in which parts of the automotive industry claimed there was too little data to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel cars,” the expert stated. “All regulatory changes regarding PHEVs should be made with extreme care and in the light of that data.”