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Plug-in hybrid cars produce almost five times more global warming pollution than official data show, as per a recent analysis.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit group. This contrasts sharply with laboratory tests, which assumed a three-quarters reduction in pollution.

Researchers studied data from in-vehicle fuel consumption monitors of 800,000 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 three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a senior analyst participating in the study. “This gap is widening and poses a significant issue. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power compared to total mileage. They determined that only a quarter of driving was done in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above lab projections. This occurred because EV motors were not strong enough to function alone, resulting to combustion motors using gasoline for nearly a third of the distance covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV emissions allowed four major carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more per year in running expenses than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with significant automotive manufacturing.

Several high-level officials have suggested PHEVs as a potential “flexibility” option to introduce in the regulation.

An independent energy policy expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert stated. “All regulatory changes concerning PHEVs should be made with utmost caution and considering that data.”