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PHEVs emit almost five times more global warming pollution than lab-reported figures show, as per a recent analysis.

Widening Gap Between Official and Real-World Emissions

Data reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. This contrasts sharply with lab tests, which suggested a 75% decrease in pollution.

Researchers studied information from onboard energy use monitors of 800,000 vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a lead researcher involved in the study. “This discrepancy is growing and poses a serious problem. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked most of the gap to overestimates of the “utility factor” – the ratio of miles travelled in battery mode relative to total distance. The team found that only 27% of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were significantly higher than lab estimates. This happened because EV motors were not strong sufficient to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions allowed several major carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating costs than would be assumed under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with significant automotive manufacturing.

Several senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which segments of the car industry claimed there was insufficient information to properly evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel cars,” the expert said. “Any policy adjustments concerning PHEVs should be made with extreme care and in the light of this evidence.”