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PHEVs produce almost five times greater global warming pollution than official figures indicate, according to a recent report.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This differs significantly with lab tests, which assumed a three-quarters decrease in emissions.

Analysts examined data from onboard fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead researcher participating in the study. “This discrepancy is growing and creates a significant issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to total distance. The team determined that just a quarter of travel was done in EV mode, while lab estimates suggested over four-fifths.

Additionally, when running in electric mode, emission levels were significantly higher than official estimates. This occurred because electric motors were not strong sufficient to operate alone, resulting to combustion motors burning fossil fuels for nearly a third of the travel covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 more annually in running expenses than is estimated under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV cars are clearly far from the truth,” commented a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the car sector and opposition from EU countries with large car manufacturing.

Some high-level officials have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One independent energy economics specialist, who was unaffiliated with the research, called the report a “highly valuable contribution” after years in which parts of the car sector claimed there was too little data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the difference between lab and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or conventional cars,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost caution and in the light of this data.”