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Plug-in hybrid cars release nearly five times more global warming emissions than official data show, as per a new report.

Growing Discrepancy In Official and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy organization. That differs sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior analyst involved in the report. “This discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power compared to overall mileage. They determined that only 27% of travel was done in electric mode, whereas official estimates assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above official estimates. This occurred because EV motors were not strong sufficient to operate independently, resulting to combustion motors burning gasoline for almost a third of the distance completed in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled four major automaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 more per year in running costs than is estimated under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV cars are clearly way off the truth,” commented a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into political debates as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car manufacturing.

Several high-level politicians have suggested plug-in hybrids as a possible “flexibility” solution to include in the regulation.

One external energy policy expert, who was not involved with the research, described the analysis a “highly valuable contribution” after years in which parts of the car industry claimed there was too little data to accurately evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they stated. “All policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of this data.”