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Plug-in hybrid electric vehicles release almost 5x more global warming emissions than official data indicate, as per a recent analysis.

Growing Discrepancy Between Official and Real-World Emissions

Statistics shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, according to research carried out by a advocacy group. This differs significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts studied data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” said a lead researcher participating in the report. “That gap is growing and poses a significant problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery mode compared to total mileage. They found that just 27% of driving was done in electric mode, while official estimates assumed over four-fifths.

Even, when running in electric mode, pollution amounts were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful enough to function independently, resulting to engines using gasoline for almost one-third of the distance covered in EV mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV emissions allowed several major carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 extra per year in operating expenses than would be assumed under lab tests.

“The bold claims that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought back into policy debates as automakers have pressed the European Union to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with large car manufacturing.

Some high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which segments of the automotive sector claimed there was too little data to properly assess actual emissions.

“These findings demonstrate, without question, that the difference in lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” the expert said. “All regulatory changes concerning PHEVs should be made with utmost caution and considering this evidence.”