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Plug-in hybrid electric vehicles release nearly five times greater global warming pollution than official figures show, as per a recent report.

Growing Discrepancy Between Official and Real-World CO2 Output

Data shows that PHEVs release only 19% lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. This contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a lead researcher participating in the report. “That gap is widening and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery mode relative to total distance. The team determined that just a quarter of travel was completed in electric mode, whereas lab assumptions suggested 84%.

Even, when running in electric mode, pollution amounts were well above official estimates. That occurred because EV motors were not strong sufficient to operate independently, resulting to engines burning fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several major carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more annually in running expenses than is assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars 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 saving money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after years in which parts of the car sector argued there was too little information to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional cars,” they said. “Any policy changes regarding PHEVs should be made with extreme care and considering this data.”