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Plug-in hybrid electric vehicles emit nearly 5x more global warming pollution than lab-reported figures indicate, as per a new report.

Widening Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, according to research conducted by a non-profit group. That differs sharply with lab estimates, which suggested a three-quarters decrease in emissions.

Analysts studied data from onboard energy use meters of 800,000 cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead analyst participating in the study. “That gap is growing and poses a serious issue. Consequently, PHEVs emit almost as much as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to total mileage. They found that just 27% of travel was done in electric mode, whereas official assumptions assumed over four-fifths.

Even, when running in electric mode, emission amounts were significantly higher than lab projections. This happened because EV motors were not strong enough to function alone, resulting to engines burning fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several large carmaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in operating expenses than is assumed under lab conditions.

“The strong claims that automakers often promote about their PHEV vehicles are obviously 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 saving costs. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have lately been drawn again into political discussions as automakers have pressed the European Union to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from member states with large automotive manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An independent energy policy expert, who was not involved with the research, called the analysis a “very useful contribution” after years in which parts of the automotive sector claimed there was too little data to accurately assess actual emissions.

“These findings show, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” they said. “All policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”