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Plug-in hybrid electric vehicles release nearly five times greater planet-heating pollution than lab-reported figures show, as per a recent analysis.

Widening Gap In Lab and Actual Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit group. That differs sharply with laboratory estimates, which assumed a three-quarters reduction in pollution.

Researchers examined information from onboard energy use monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a lead researcher involved in the study. “That gap is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power compared to total distance. The team found that just a quarter of driving was done in EV mode, while lab estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution levels were well above official projections. That happened because EV motors were not strong enough to operate alone, resulting to engines burning fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four major carmaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more annually in running expenses than is estimated under lab tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the truth,” stated a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have lately been drawn again into policy discussions as automakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with large car manufacturing.

Some senior officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the legislation.

An external energy economics specialist, who was unaffiliated with the study, called the report a “very useful addition” after years in which parts of the automotive industry argued there was insufficient information to accurately evaluate actual emissions.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert stated. “All policy changes concerning PHEVs should be made with extreme care and considering this evidence.”