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PHEVs emit almost five times greater global warming emissions than official figures show, according to a recent analysis.

Widening Discrepancy In Official and Real-World Emissions

Data shows that PHEVs release only 19% lower CO₂ than traditional gas and diesel cars, according to analysis carried out by a advocacy organization. That contrasts sharply with lab tests, which assumed a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a senior analyst participating in the report. “That discrepancy is widening and poses a serious issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in electric power relative to total distance. They determined that only 27% of travel was done in electric mode, whereas official estimates assumed 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab estimates. That happened because electric motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for almost one-third of the distance covered in EV mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV CO2 output allowed several major automaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in running expenses than would be assumed under lab tests.

“The bold statements that automakers like to make about their PHEV cars are obviously far from the mark,” stated a automotive expert. “Buyers are being misled into believing 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 fuel consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have lately been brought back into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from member states with significant automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

An independent energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the automotive sector argued there was too little information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert said. “All regulatory adjustments concerning PHEVs should be made with utmost caution and considering this data.”