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Plug-in hybrid cars produce almost five times greater planet-heating emissions than lab-reported figures indicate, as per a recent analysis.

Growing Gap Between Lab and Actual Emissions

Data reveals that PHEVs emit just 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a advocacy group. This contrasts significantly with laboratory tests, which suggested a three-quarters decrease in pollution.

Analysts examined information from onboard energy use monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a lead analyst participating in the study. “This discrepancy is growing and creates a significant problem. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery mode relative to overall distance. They determined that only a quarter of travel was done in electric mode, while lab estimates assumed 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors burning gasoline for almost a third of the travel completed in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in operating costs than is assumed under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and resistance from member states with significant car industries.

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

An independent energy policy expert, who was not involved with the research, described the report a “very useful contribution” after a long period in which parts of the car sector claimed there was too little data to accurately assess actual CO2 output.

“These findings show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost caution and considering that evidence.”