🔗 Share this article

Plug-in hybrid cars produce almost 5x more planet-heating emissions than lab-reported figures indicate, according to a new analysis.

Widening Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis carried out by a non-profit organization. This contrasts sharply with laboratory tests, which assumed a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst participating in the report. “That discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Behind the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery mode relative to total distance. They found that just 27% of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Even, when operating in EV mode, pollution amounts were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to engines burning fossil fuels for almost one-third of the travel covered in electric mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled several large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in running costs than would be assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously way off the truth,” stated a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with large automotive industries.

Several senior officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the regulation.

One independent energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which segments of the automotive industry argued there was insufficient information to accurately assess real-world emissions.

“The results demonstrate, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme care and in the light of this data.”