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Plug-in hybrid cars emit almost five times greater planet-heating pollution than official data indicate, as per a new analysis.

Growing Gap In Official and Real-World CO2 Output

Data shows that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, based on research conducted by a non-profit group. That differs significantly with lab estimates, which suggested a 75% decrease in pollution.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a senior researcher involved in the report. “That discrepancy is growing and poses a significant issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery mode compared to overall mileage. They found that only 27% of driving was completed in EV mode, whereas lab assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were well above official estimates. That occurred because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using gasoline for nearly one-third of the travel completed in electric mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ standards.

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

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn again into political discussions as automakers have lobbied the EU to relax CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and opposition from member states with large car industries.

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

One independent energy economics expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the automotive industry claimed there was too little information to accurately assess actual CO2 output.

“These findings demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be made with utmost care and considering this data.”