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PHEVs release nearly five times greater planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Widening Discrepancy In Lab and Actual Emissions

Data shows that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, based on research conducted by a advocacy group. This differs sharply with lab estimates, which suggested a 75% reduction in pollution.

Researchers examined information from onboard energy use meters of 800,000 vehicles registered in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” stated a senior researcher participating in the report. “This gap is growing and creates a serious issue. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in electric mode compared to overall distance. The team found that just 27% of travel was done in electric mode, whereas lab estimates assumed 84%.

Even, when operating in EV mode, emission levels were significantly higher than lab projections. That happened because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four major automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in running costs than would be estimated under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV cars are obviously far from the mark,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought again into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with significant automotive industries.

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

An independent energy policy specialist, who was not involved with the study, called the analysis a “highly valuable contribution” after years in which parts of the automotive industry argued there was insufficient information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel vehicles,” the expert said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and considering that data.”