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Plug-in hybrid electric vehicles produce almost 5x more global warming emissions than lab-reported figures show, according to a recent report.

Growing Gap In Official and Real-World Emissions

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel cars, based on research carried out by a non-profit organization. This differs sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers studied data from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” stated a lead analyst participating in the report. “That gap is widening and poses a significant issue. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts linked most of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to total distance. They found that only 27% of driving was done in electric mode, while lab assumptions suggested over four-fifths.

Even, when running in electric mode, emission levels were significantly higher than official estimates. That happened because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors using gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several large automaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 more per year in operating expenses than would be estimated under lab conditions.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the mark,” commented a automotive analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been brought back into political discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large car industries.

Some high-level politicians have proposed plug-in hybrids as a potential “compromise” solution to include in the regulation.

One independent energy economics specialist, who was not involved with the study, called the analysis a “very useful addition” after years in which segments of the car sector argued there was too little data to properly evaluate actual emissions.

“The results demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “Any regulatory changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”