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Plug-in hybrid electric vehicles produce almost 5x more global warming emissions than official data indicate, according to a recent analysis.

Growing Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to research carried out by a non-profit group. This differs significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” stated a lead analyst participating in the report. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Reasons Behind the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery mode compared to total mileage. The team found that just 27% of driving was done in EV mode, whereas official estimates suggested 84%.

Even, when running in EV mode, emission amounts were significantly higher than official projections. That occurred because EV motors were insufficiently powerful sufficient to function alone, leading to engines burning gasoline for almost one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed four large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in running costs than is assumed under laboratory conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and opposition from member states with significant automotive industries.

Several high-level politicians have proposed PHEVs as a possible “flexibility” option to include in the regulation.

An independent energy policy expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the car industry argued there was insufficient information to accurately evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of this evidence.”