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PHEVs release nearly five times greater global warming pollution than official data indicate, according to a new report.

Growing Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy group. That differs sharply with lab tests, which assumed a three-quarters decrease in pollution.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” said a lead analyst participating in the report. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery power compared to total mileage. The team found that only 27% of driving was done in EV mode, whereas official assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than official projections. That happened because EV motors were not strong sufficient to operate alone, resulting to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several major carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more annually in running costs than is estimated under laboratory tests.

“The bold claims that automakers often promote about their PHEV vehicles are clearly far from the truth,” stated a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Political Debate and Industry Lobbying

Hybrid cars have lately been brought again into policy debates as automakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with large car industries.

Some senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the regulation.

An external energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which parts of the car sector argued there was insufficient information to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” the expert stated. “All regulatory changes regarding PHEVs should be made with utmost caution and considering that data.”