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PHEVs produce almost five times more global warming pollution than lab-reported data show, according to a new analysis.

Widening Gap Between Lab and Actual CO2 Output

Data shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, according to research conducted by a advocacy group. This differs significantly with lab tests, which assumed a 75% decrease in emissions.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a senior analyst participating in the study. “That gap is widening and creates a serious problem. Consequently, PHEVs emit almost as much as gasoline cars.”

Key Factors Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total distance. The team determined that only a quarter of travel was done in electric mode, whereas official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above official projections. This happened because electric motors were not strong sufficient to operate independently, leading to engines using gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled several major automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more per year in operating expenses than is assumed under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have lately been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant car manufacturing.

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

An independent energy policy specialist, who was not involved with the study, described the analysis a “very useful addition” after years in which parts of the automotive sector argued there was too little data to properly assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be made with utmost care and in the light of that data.”