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Plug-in hybrid electric vehicles emit nearly five times greater global warming emissions than official figures indicate, as per a new report.

Growing Discrepancy In Official and Real-World Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. That differs sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts studied data from onboard fuel consumption monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a senior researcher involved in the study. “This discrepancy is growing and poses a serious issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power compared to overall mileage. They found that just 27% of travel was completed in electric mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than official estimates. That happened because electric motors were not strong enough to operate alone, resulting to combustion motors burning fossil fuels for nearly one-third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions allowed several major automaker companies to escape more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in running costs than is assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV cars are clearly far from the truth,” commented a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been brought again into political debates as automakers have pressed the EU to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and resistance from EU countries with large car manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

One independent energy economics specialist, who was not involved with the study, called the analysis a “very useful addition” after years in which parts of the car industry argued there was insufficient data to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the gap between lab and actual PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with extreme care and in the light of that data.”