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PHEVs emit almost five times greater global warming emissions than official figures show, according to a new analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Data shows that PHEVs emit only 19% less CO₂ than traditional gas and diesel vehicles, according to research carried out by a advocacy group. This contrasts significantly with laboratory tests, which assumed a three-quarters reduction in pollution.

Analysts examined data from onboard energy use monitors of 800,000 cars registered in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” said a lead analyst participating in the study. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in electric mode relative to overall distance. They found that just a quarter of travel was done in electric mode, while lab estimates assumed over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful enough to operate independently, leading to combustion motors using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output enabled four major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay about €500 extra annually in running expenses than would be assumed under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” stated a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid vehicles have lately been drawn again into policy discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with significant automotive industries.

Several high-level officials have suggested PHEVs as a possible “compromise” option to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, described the analysis a “very useful contribution” after a long period in which segments of the automotive industry claimed there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, without question, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel cars,” they stated. “All regulatory adjustments concerning PHEVs should be made with utmost caution and in the light of this data.”