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Plug-in hybrid electric vehicles produce almost 5x more planet-heating emissions than lab-reported data show, according to a recent analysis.

Growing Discrepancy In Lab and Actual CO2 Output

Statistics reveals that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. That differs significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” stated a senior analyst participating in the study. “This gap is widening and creates a significant problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in electric mode compared to overall mileage. The team determined that only 27% of driving was completed in electric mode, whereas official estimates suggested over four-fifths.

Even, when operating in EV mode, emission amounts were significantly higher than official estimates. That happened because electric motors were insufficiently powerful enough to function independently, resulting to engines using gasoline for nearly one-third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output allowed four major automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more per year in operating costs than would be assumed under laboratory tests.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the EU to relax CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large car manufacturing.

Some senior officials have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An independent energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after a long period in which segments of the car sector argued there was insufficient data to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with utmost caution and in the light of this evidence.”