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PHEVs release almost five times more global warming pollution than official data indicate, as per a new report.

Widening Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy group. This differs significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Researchers examined data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” said a lead researcher participating in the study. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to overall distance. They determined that just 27% of travel was completed in EV mode, whereas official estimates assumed 84%.

Additionally, when running in electric mode, pollution amounts were well above official projections. This happened because electric motors were not strong sufficient to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra annually in operating costs than is estimated under lab tests.

“The bold claims that automakers like to make about their plug-in hybrid cars are obviously far from the truth,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been drawn back into policy debates as automakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with large car industries.

Some senior officials have proposed plug-in hybrids as a potential “flexibility” option to introduce in the regulation.

One independent energy economics specialist, who was not involved with the research, described the report a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little data to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” the expert said. “All policy adjustments concerning PHEVs should be made with extreme caution and in the light of this data.”