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Plug-in hybrid cars release nearly five times more planet-heating emissions than lab-reported figures indicate, according to a recent analysis.

Growing Gap In Official and Actual Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel vehicles, according to research carried out by a non-profit organization. That contrasts sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” said a lead analyst participating in the study. “That gap is widening and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power relative to total mileage. They found that just 27% of travel was done in electric mode, while official estimates suggested 84%.

Even, when running in electric mode, emission amounts were well above lab estimates. This occurred because EV motors were insufficiently powerful sufficient to function alone, leading to combustion motors burning fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed several major automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 extra per year in operating costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Automotive Pressure

Hybrid vehicles have recently been brought back into political debates as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and resistance from member states with large automotive industries.

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

One independent energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after years in which parts of the car sector claimed there was insufficient information to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert said. “All policy adjustments regarding PHEVs should be implemented with extreme care and considering that data.”