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PHEVs release nearly five times more planet-heating emissions than official figures show, as per a new analysis.

Widening Gap Between Lab and Actual Emissions

Statistics shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a advocacy group. That differs significantly with laboratory tests, which suggested a three-quarters decrease in emissions.

Analysts studied data from onboard fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior analyst involved in the study. “That gap is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of miles driven in electric power compared to total distance. They determined that just a quarter of travel was done in EV mode, while lab assumptions assumed 84%.

Additionally, when operating in electric mode, emission amounts were well above lab projections. That occurred because electric motors were not strong sufficient to function alone, resulting to engines burning gasoline for almost one-third of the travel covered in EV mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV emissions enabled several major carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

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

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” stated a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the car industry and opposition from member states with significant car manufacturing.

Some high-level politicians have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

An external energy economics expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which parts of the automotive industry argued there was insufficient information to properly assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” the expert stated. “All regulatory changes regarding PHEVs should be made with utmost caution and considering this data.”