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Plug-in hybrid cars release nearly 5x more global warming emissions than official figures show, according to a recent report.

Widening Discrepancy Between Lab and Actual Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a advocacy organization. That contrasts significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts studied information from onboard energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst participating in the report. “This gap is growing and creates a serious problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to overall distance. They determined that only 27% of travel was done in electric mode, while lab assumptions assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were not strong sufficient to operate independently, resulting to combustion motors burning gasoline for almost one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed four large carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more annually in operating expenses than would be assumed under lab tests.

“The bold statements that manufacturers often promote about their PHEV vehicles are obviously far from the mark,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have recently been brought again into policy discussions as carmakers have pressed the European Union to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant automotive industries.

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

An external energy policy expert, who was not involved with the study, called the report a “very useful addition” after years in which segments of the automotive sector argued there was too little information to accurately assess actual emissions.

“These findings demonstrate, without question, that the difference between official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or conventional cars,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost caution and considering that data.”