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PHEVs emit almost five times more planet-heating emissions than lab-reported figures indicate, as per a new analysis.

Widening Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a advocacy group. This contrasts significantly with lab tests, which assumed a 75% reduction in pollution.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are falling,” stated a senior analyst involved in the study. “This gap is growing and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power compared to overall mileage. They determined that just a quarter of driving was done in EV mode, while official assumptions assumed 84%.

Even, when operating in electric mode, emission levels were significantly higher than official estimates. That occurred because EV motors were not strong enough to operate independently, resulting to combustion motors burning gasoline for nearly one-third of the travel covered in EV mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in running expenses than would be assumed under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought again into political discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant car industries.

Several high-level officials have proposed PHEVs as a potential “compromise” solution to include in the regulation.

An independent energy economics expert, who was not involved with the research, described the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little information to accurately assess real-world CO2 output.

“These findings show, without question, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with utmost care and considering this data.”