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Plug-in hybrid cars release almost five times greater global warming emissions than official data show, according to a new analysis.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, based on analysis conducted by a advocacy organization. That differs sharply with lab tests, which suggested a three-quarters decrease in pollution.

Researchers examined information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a senior researcher involved in the report. “This gap is growing and poses a significant issue. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in electric power compared to overall mileage. They determined that only 27% of travel was completed in EV mode, while official assumptions assumed 84%.

Even, when running in electric mode, emission amounts were well above lab estimates. This happened because EV motors were insufficiently powerful sufficient to function alone, resulting to combustion motors burning fossil fuels for almost a third of the distance covered in electric mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in running expenses than is assumed under laboratory tests.

“The strong statements that automakers often promote about their PHEV cars are clearly way off the truth,” stated a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Automotive Lobbying

Hybrid cars have lately been drawn again into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large automotive manufacturing.

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

One independent energy policy specialist, 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 accurately assess actual emissions.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or diesel cars,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost caution and considering this evidence.”