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Plug-in hybrid electric vehicles produce nearly five times more global warming pollution than lab-reported data indicate, according to a recent report.

Growing Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a advocacy organization. This contrasts significantly with lab estimates, which assumed a 75% decrease in pollution.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a senior researcher participating in the report. “This discrepancy is growing and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to overall mileage. They found that only 27% of driving was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were well above lab projections. That occurred because EV motors were insufficiently powerful sufficient to operate independently, leading to engines burning gasoline for almost a third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled four major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more annually in running costs than would be assumed under laboratory tests.

“The bold statements that automakers often promote about their PHEV cars are clearly way off the truth,” stated a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been drawn again into policy debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car sector and resistance from member states with large car manufacturing.

Several senior politicians have proposed plug-in hybrids as a potential “compromise” option to introduce in the legislation.

One independent energy economics specialist, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which segments of the automotive sector claimed there was insufficient data to accurately assess real-world CO2 output.

“The results show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel cars,” they said. “Any policy changes regarding PHEVs should be implemented with utmost care and considering this data.”