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Plug-in hybrid electric vehicles release nearly five times greater global warming emissions than lab-reported data indicate, as per a recent analysis.

Widening Gap In Lab and Real-World Emissions

Data reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel cars, based on analysis carried out by a advocacy organization. This contrasts significantly with lab estimates, which assumed a 75% reduction in pollution.

Analysts studied information from onboard fuel consumption monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a senior researcher involved in the report. “This gap is widening and creates a significant problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric power compared to total mileage. They determined that just a quarter of driving was done in EV mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, emission levels were well above lab estimates. That occurred because electric motors were insufficiently powerful enough to function alone, leading to combustion motors burning gasoline for nearly a third of the distance completed in electric mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV emissions enabled four major automaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay about €500 more annually in operating expenses than would be estimated under lab tests.

“The bold statements that automakers like to make about their PHEV vehicles are clearly far from the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought again into policy debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large automotive industries.

Some high-level officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An external energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was too little data to accurately evaluate actual emissions.

“The results show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be implemented with utmost caution and in the light of this data.”