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Plug-in hybrid electric vehicles produce nearly five times greater global warming emissions than official figures show, as per a recent report.

Growing Discrepancy Between Official and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit organization. That differs sharply with lab estimates, which suggested a 75% reduction in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” stated a senior analyst participating in the report. “This gap is widening and poses a serious issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to overall distance. They found that just 27% of travel was completed in electric mode, whereas lab assumptions assumed 84%.

Additionally, when operating in electric mode, pollution amounts were well above lab estimates. That happened because electric motors were insufficiently powerful enough to function independently, leading to engines burning fossil fuels for nearly a third of the travel covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV emissions enabled four large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in operating costs than would be estimated under lab conditions.

“The bold claims that automakers often promote about their PHEV cars are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. 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 car industries.

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

An external energy economics specialist, who was unaffiliated with the research, described the analysis a “highly valuable addition” after a long period in which parts of the car sector argued there was too little data to accurately evaluate real-world emissions.

“The results demonstrate, without question, that the gap between official and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering that evidence.”