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Plug-in hybrid cars release almost 5x greater global warming pollution than lab-reported figures indicate, as per a recent report.

Widening Gap Between Official and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a advocacy group. That contrasts significantly with lab tests, which suggested a 75% decrease in pollution.

Researchers studied data from onboard fuel consumption monitors of eight hundred thousand cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” stated a senior researcher participating in the study. “This discrepancy is growing and poses a serious issue. Consequently, PHEVs emit nearly as much as petrol cars.”

Key Factors Behind the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in battery mode relative to overall distance. The team found that just 27% of travel was done in electric mode, while official estimates assumed 84%.

Even, when operating in EV mode, emission levels were significantly higher than official projections. That happened because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions allowed several major automaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 extra per year in running costs than would be estimated under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been drawn back into political debates as carmakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and opposition from EU countries with large car industries.

Several senior officials have proposed PHEVs as a possible “flexibility” option to introduce in the legislation.

One independent energy economics specialist, who was not involved with the research, described the analysis a “very useful addition” after years in which segments of the car sector claimed there was too little information to accurately assess actual emissions.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they stated. “Any regulatory changes regarding PHEVs should be implemented with extreme care and in the light of this data.”