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PHEVs produce nearly 5x greater global warming pollution than official figures show, according to a recent report.

Widening Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a non-profit group. This contrasts sharply with laboratory tests, which assumed a three-quarters decrease in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” stated a senior analyst participating in the report. “That gap is widening and poses a serious problem. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to overall distance. The team determined that only a quarter of driving was completed in electric mode, while lab estimates assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were well above official estimates. That occurred because EV motors were not strong enough to operate independently, leading to combustion motors burning gasoline for almost a third of the distance covered in electric mode.

Policy and Financial Consequences

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

Additionally, owners of PHEVs could spend about €500 extra annually in operating expenses than would be estimated under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than standard gas and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid cars have recently been brought back into policy discussions as automakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with large car industries.

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

One external energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after years in which parts of the automotive sector argued there was too little data to accurately evaluate actual emissions.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” the expert said. “Any policy adjustments concerning PHEVs should be made with utmost care and considering this evidence.”