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PHEVs release almost 5x greater planet-heating emissions than lab-reported data show, as per a new analysis.

Widening Gap In Lab and Actual Emissions

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy organization. This contrasts sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of 800,000 cars sold in Europe from 2021 and 2023. They discovered 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.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst involved in the report. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to total mileage. They found that only 27% of travel was done in electric mode, whereas official estimates assumed 84%.

Even, when operating in EV mode, emission amounts were significantly higher than lab estimates. That occurred because EV motors were not strong sufficient to operate independently, leading to combustion motors burning fossil fuels for nearly one-third of the distance completed in EV mode.

Policy and Economic Implications

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

Additionally, owners of PHEVs could spend approximately €500 extra annually in operating costs than would be assumed under lab conditions.

“The strong statements that automakers like to make about their PHEV cars are obviously far from the truth,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn again into policy debates as automakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with significant car manufacturing.

Several senior officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One independent energy policy specialist, who was not involved with the research, described the report a “highly valuable contribution” after years in which parts of the car sector claimed there was too little information to properly evaluate actual CO2 output.

“These findings show, without question, that the difference in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they said. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of that evidence.”