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Plug-in hybrid cars release almost 5x greater planet-heating pollution than lab-reported data show, as per a recent analysis.

Growing Gap Between Lab and Actual Emissions

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to research carried out by a advocacy group. That contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” stated a senior researcher participating in the study. “This discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in battery power compared to total mileage. The team determined that just a quarter of driving was completed in EV mode, whereas lab assumptions suggested 84%.

Even, when running in EV mode, pollution levels were significantly higher than lab estimates. That occurred because EV motors were not strong enough to function independently, resulting to engines burning fossil fuels for almost one-third of the travel covered in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV CO2 output allowed several large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 extra annually in running expenses than would be assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn back into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from EU countries with large automotive manufacturing.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

An independent energy policy expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the car industry claimed there was insufficient data to accurately assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert stated. “Any policy adjustments concerning PHEVs should be implemented with extreme care and considering this evidence.”