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PHEVs emit nearly 5x greater global warming pollution than official data show, according to a new report.

Widening Gap In Official and Real-World Emissions

Data shows that PHEVs release only 19% lower CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior analyst participating in the report. “This discrepancy is growing and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric power relative to overall distance. The team determined that only 27% of driving was completed in electric mode, whereas official estimates suggested 84%.

Even, when operating in electric mode, emission amounts were significantly higher than official estimates. This happened because EV motors were not strong sufficient to function independently, resulting to combustion motors burning gasoline for almost one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV emissions enabled four large carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more per year in operating expenses than is estimated under lab conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with large automotive manufacturing.

Some senior officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

An external energy economics expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little information to properly assess real-world CO2 output.

“These findings show, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional vehicles,” they stated. “All policy adjustments regarding PHEVs should be made with utmost caution and considering this data.”