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PHEVs release nearly 5x greater planet-heating emissions than official figures show, according to a recent analysis.

Growing Gap Between Official and Actual CO2 Output

Data shows that PHEVs release just 19% lower CO₂ than conventional petrol and diesel cars, according to research conducted by a advocacy organization. That differs sharply with lab tests, which assumed a three-quarters reduction in pollution.

Analysts studied information from onboard fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” stated a lead analyst participating in the report. “This gap is growing and creates a significant problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to total distance. The team found that just 27% of driving was done in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, pollution levels were significantly higher than official estimates. That occurred because electric motors were not strong enough to operate independently, resulting to engines burning fossil fuels for nearly a third of the distance covered in EV mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several large automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in operating costs than is assumed under lab conditions.

“The bold claims that automakers like to make about their PHEV vehicles are obviously far from the mark,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Hybrid cars have lately been brought again into policy discussions as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from EU countries with large car manufacturing.

Several senior officials have proposed PHEVs as a possible “flexibility” option to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which parts of the car industry argued there was too little data to accurately assess real-world CO2 output.

“The results show, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional cars,” the expert said. “All policy changes regarding PHEVs should be made with utmost caution and considering that evidence.”