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Plug-in hybrid electric vehicles release almost 5x greater global warming pollution than lab-reported data show, as per a recent analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research conducted by a advocacy organization. This contrasts significantly with lab estimates, which suggested a 75% decrease in emissions.

Researchers studied information from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” stated a senior analyst participating in the report. “This gap is widening and creates a serious problem. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode relative to total mileage. The team determined that only a quarter of driving was completed in EV mode, while lab estimates suggested 84%.

Even, when running in EV mode, pollution levels were significantly higher than lab estimates. That happened because EV motors were insufficiently powerful sufficient to function alone, leading to engines using gasoline for almost one-third of the travel covered in EV mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 extra annually in operating costs than is estimated under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the mark,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Hybrid cars have recently been brought again into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced heavy lobbying from the car sector and opposition from member states with large automotive manufacturing.

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

An independent energy economics expert, who was unaffiliated with the research, described the report a “very useful contribution” after years in which segments of the car sector argued there was too little data to accurately evaluate actual CO2 output.

“These findings demonstrate, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with utmost care and considering that evidence.”