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Plug-in hybrid electric vehicles produce almost five times greater global warming pollution than lab-reported data show, according to a recent report.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy group. That contrasts significantly with lab tests, which assumed a 75% decrease in emissions.

Analysts examined data from onboard fuel consumption monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” stated a lead analyst participating in the report. “This gap is growing and poses a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to overall mileage. They determined that only 27% of driving was done in EV mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than lab projections. That occurred because EV motors were not strong sufficient to function alone, resulting to combustion motors using fossil fuels for nearly a third of the travel covered in electric mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions allowed four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The strong claims that automakers like to make about their PHEV cars are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy discussions as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from EU countries with large automotive manufacturing.

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

An external energy policy expert, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which parts of the car industry claimed there was insufficient data to properly assess actual CO2 output.

“The results demonstrate, without question, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with extreme care and considering that evidence.”