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Plug-in hybrid electric vehicles release almost five times more planet-heating emissions than official data show, as per a recent analysis.

Growing Discrepancy In Lab and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit group. This contrasts significantly with lab tests, which assumed a 75% decrease in emissions.

Researchers examined information from onboard energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior analyst participating in the study. “That discrepancy is widening and poses a significant issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power compared to total distance. They found that only a quarter of travel was done in EV mode, while official estimates assumed 84%.

Even, when operating in EV mode, emission amounts were significantly higher than lab projections. This happened because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors using gasoline for nearly a third of the travel covered in EV mode.

Regulatory and Financial Consequences

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

Furthermore, drivers of PHEVs would pay about €500 more per year in operating costs than would be estimated under laboratory tests.

“The strong claims that automakers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than standard gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large automotive industries.

Several high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which segments of the car industry argued there was too little information to properly assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering this evidence.”