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Plug-in hybrid cars produce nearly 5x more planet-heating pollution than lab-reported figures indicate, according to a new analysis.

Widening Gap In Official and Actual Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit organization. This differs sharply with laboratory estimates, which suggested a three-quarters decrease in emissions.

Analysts examined data from onboard energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a senior researcher involved in the report. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in electric power relative to overall mileage. They determined that just a quarter of travel was done in EV mode, while lab assumptions suggested over four-fifths.

Even, when operating in electric mode, pollution levels were well above lab projections. This occurred because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using fossil fuels for almost one-third of the travel completed in EV mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output enabled several major carmaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 more annually in running expenses than would be assumed under laboratory conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought back into policy discussions as automakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with significant automotive industries.

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

One independent energy policy specialist, who was not involved with the study, called the analysis a “very useful addition” after a long period in which segments of the automotive industry argued there was insufficient information to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of that data.”