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Plug-in hybrid cars produce almost 5x more global warming pollution than lab-reported figures show, according to a new analysis.

Widening Gap Between Official and Actual Emissions

Statistics reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, based on research conducted by a advocacy organization. This contrasts significantly with lab tests, which suggested a three-quarters decrease in pollution.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are falling,” said a senior researcher participating in the study. “That discrepancy is widening and creates a significant problem. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery mode relative to overall distance. They determined that only 27% of travel was done in electric mode, whereas official assumptions assumed 84%.

Additionally, when running in electric mode, emission amounts were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful sufficient to function alone, resulting to combustion motors burning gasoline for almost a third of the travel completed in EV mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV emissions enabled several large carmaker companies to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in operating costs than would be assumed under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Industry Lobbying

Hybrid cars have lately been drawn back into political discussions as carmakers have lobbied 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 industry and resistance from member states with large car manufacturing.

Several senior officials have suggested plug-in hybrids as a potential “compromise” option to include in the regulation.

An external energy policy specialist, who was unaffiliated with the research, called the analysis a “highly valuable addition” after years in which segments of the automotive industry argued there was insufficient data to properly assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional vehicles,” they said. “All regulatory changes concerning PHEVs should be made with utmost care and considering this data.”