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PHEVs release almost 5x greater global warming emissions than official data indicate, according to a new analysis.

Widening Gap In Official and Real-World Emissions

Statistics shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, based on research conducted by a advocacy organization. This differs significantly with laboratory tests, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a lead analyst participating in the study. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric power compared to total distance. The team found that just 27% of driving was completed in electric mode, while lab assumptions suggested 84%.

Even, when running in electric mode, pollution amounts were significantly higher than official estimates. That occurred because EV motors were not strong enough to operate independently, leading to combustion motors using fossil fuels for nearly a third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to estimates, the underestimation of PHEV emissions allowed four major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn again into political debates as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the car sector and opposition from member states with significant automotive industries.

Some senior politicians have proposed PHEVs as a potential “compromise” option to include in the regulation.

An external energy policy specialist, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was insufficient information to accurately evaluate actual emissions.

“These findings show, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering this evidence.”