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Plug-in hybrid electric vehicles emit almost 5x greater planet-heating pollution than lab-reported figures indicate, as per a recent analysis.

Growing Gap In Official and Real-World Emissions

Data shows that PHEVs release only one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a non-profit group. This differs sharply with laboratory tests, which suggested a three-quarters decrease in emissions.

Analysts examined information from onboard fuel consumption monitors of 800,000 cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” said a senior researcher participating in the report. “This gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total distance. The team found that just a quarter of driving was completed in EV mode, while lab assumptions suggested over four-fifths.

Even, when operating in EV mode, emission amounts were significantly higher than official projections. That happened because electric motors were not strong enough to operate alone, resulting to engines burning gasoline for almost a third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV emissions allowed four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

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

“The bold statements that automakers often promote about their PHEV vehicles are clearly way off the mark,” stated a automotive analyst. “Buyers 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 cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant automotive manufacturing.

Some senior officials have suggested PHEVs as a possible “compromise” option to include in the legislation.

An external energy policy expert, who was not involved with the research, called the report a “highly valuable addition” after years in which parts of the automotive sector claimed there was insufficient information to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the gap in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “Any policy adjustments concerning PHEVs should be made with utmost care and in the light of this data.”