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PHEVs release almost five times greater global warming emissions than lab-reported figures show, as per a new analysis.

Growing Gap In Lab and Real-World Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit organization. That differs sharply with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers examined data from onboard fuel consumption meters of 800,000 cars registered in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” said a senior analyst involved in the report. “That discrepancy is widening and creates a serious problem. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles travelled in battery mode compared to total distance. They found that only 27% of travel was done in EV mode, whereas official estimates suggested over four-fifths.

Additionally, when running in electric mode, emission amounts were significantly higher than lab projections. This happened because electric motors were not strong sufficient to function alone, resulting to combustion motors burning fossil fuels for almost a third of the travel completed in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed four major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 more annually in running costs than would be assumed under laboratory conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are obviously far from the mark,” commented a automotive analyst. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn back into policy discussions as carmakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant automotive manufacturing.

Several senior officials have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

An independent energy policy expert, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which segments of the car sector argued there was insufficient information to accurately evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they stated. “Any regulatory changes concerning PHEVs should be implemented with utmost care and in the light of that data.”