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PHEVs produce nearly five times more planet-heating emissions than lab-reported data show, according to a recent analysis.

Growing Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a non-profit organization. That differs sharply with laboratory tests, which suggested a 75% decrease in pollution.

Researchers examined information from onboard fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” stated a lead analyst involved in the report. “That gap is growing and poses a serious problem. As a result, PHEVs emit almost as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power relative to total mileage. They determined that just 27% of travel was done in electric mode, whereas official assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission amounts were well above official projections. This happened because EV motors were insufficiently powerful enough to function independently, resulting to combustion motors burning fossil fuels for almost one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output allowed four major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average 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 statements that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been drawn again into policy debates as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with large automotive manufacturing.

Some senior officials have suggested PHEVs as a possible “flexibility” option to include in the regulation.

An independent energy economics expert, who was not involved with the research, described the analysis a “very useful addition” after a long period in which segments of the automotive sector argued there was too little data to properly assess actual emissions.

“These findings demonstrate, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ output is much, much greater than for petrol or diesel cars,” they said. “All policy adjustments regarding PHEVs should be made with utmost care and considering that evidence.”