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Plug-in hybrid cars release almost five times greater global warming emissions than official data indicate, as per a recent report.

Growing Discrepancy In Lab and Actual Emissions

Statistics shows that PHEVs emit just 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a advocacy organization. This contrasts sharply with lab tests, which suggested a three-quarters reduction in pollution.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” said a lead analyst participating in the study. “This discrepancy is growing and poses a serious problem. As a result, PHEVs emit almost as much as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers linked most of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric mode compared to overall distance. The team determined that just a quarter of travel was completed in electric mode, whereas lab assumptions suggested 84%.

Even, when running in EV mode, emission levels were significantly higher than official estimates. This occurred because EV motors were insufficiently powerful enough to operate alone, leading to combustion motors using gasoline for almost a third of the distance covered in electric mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed several major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra annually in running costs than is assumed under laboratory tests.

“The strong claims that automakers often promote about their PHEV vehicles are obviously way off the mark,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have recently been brought back into political debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with large automotive manufacturing.

Some high-level politicians have suggested PHEVs as a possible “flexibility” solution to include in the legislation.

An external energy policy specialist, who was not involved with the study, described the report a “very useful addition” after a long period in which segments of the car sector argued there was too little information to accurately assess actual emissions.

“These findings demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is much, much larger than for petrol or conventional cars,” they said. “All regulatory changes regarding PHEVs should be implemented with extreme care and considering that evidence.”