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Plug-in hybrid electric vehicles emit nearly 5x more planet-heating pollution than official data indicate, according to a recent report.

Growing Gap In Official and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than conventional gas and diesel vehicles, according to research conducted by a advocacy organization. That contrasts significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “That discrepancy is widening and poses a serious issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery mode compared to total mileage. The team determined that only 27% of driving was completed in electric mode, whereas official assumptions suggested over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than lab projections. This occurred because electric motors were insufficiently powerful enough to function alone, resulting to engines burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions allowed several major carmaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more per year in operating expenses than would be estimated under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been brought again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large automotive industries.

Some senior officials have proposed PHEVs as a potential “compromise” solution to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after years in which segments of the automotive sector argued there was insufficient data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be made with extreme care and considering this data.”