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Plug-in hybrid cars release nearly 5x more planet-heating emissions than official data show, as per a recent analysis.

Growing Discrepancy In Official and Real-World Emissions

Data shows that PHEVs release just one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis carried out by a non-profit group. That differs sharply with lab tests, which suggested a three-quarters reduction in pollution.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” said a lead analyst involved in the study. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs emit almost as much as petrol cars.”

Primary Reasons Behind the Discrepancy

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode relative to total mileage. The team found that just 27% of driving was completed in EV mode, whereas official estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to function independently, leading to combustion motors burning fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled several large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 more annually in operating costs than is assumed under laboratory conditions.

“The bold claims that automakers often promote about their PHEV vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have lately been brought back into political debates as carmakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant automotive manufacturing.

Some high-level politicians have suggested PHEVs as a possible “flexibility” option to include in the regulation.

One independent energy policy expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient information to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel vehicles,” the expert said. “All policy adjustments regarding PHEVs should be implemented with utmost caution and considering that data.”