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PHEVs emit nearly 5x greater planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Growing Discrepancy Between Lab and Actual Emissions

Statistics shows that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy organization. That differs significantly with lab estimates, which suggested a three-quarters decrease in emissions.

Researchers studied data from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior analyst involved in the study. “That discrepancy is growing and poses a serious issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to total distance. They found that only a quarter of driving was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several large automaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 extra annually in operating costs than is estimated under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” stated a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have lately been drawn back into policy debates as automakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with significant automotive manufacturing.

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

An external energy policy specialist, who was not involved with the study, called the analysis a “highly valuable addition” after years in which parts of the car industry claimed there was too little information to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “All policy changes regarding PHEVs should be implemented with utmost care and considering that data.”