🔗 Share this article

Plug-in hybrid electric vehicles emit nearly five times more planet-heating pollution than official data indicate, according to a recent report.

Growing Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit group. This differs significantly with laboratory tests, which suggested a three-quarters decrease in pollution.

Analysts examined information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” said a senior researcher involved in the study. “This gap is widening and poses a significant problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Analysts linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to total distance. They determined that just a quarter of travel was done in electric mode, while lab assumptions assumed over four-fifths.

Even, when running in EV mode, pollution levels were well above official estimates. This occurred because electric motors were not strong sufficient to function independently, resulting to engines using gasoline for almost a third of the distance covered in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled four large carmaker companies to escape over €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 extra annually in operating costs than would be estimated under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have lately been drawn again into political debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with significant automotive manufacturing.

Several senior officials have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

An independent energy policy expert, who was not involved with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry argued there was too little data to accurately assess actual CO2 output.

“These findings demonstrate, without question, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they stated. “Any policy changes regarding PHEVs should be implemented with utmost care and in the light of this data.”