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PHEVs emit nearly five times greater planet-heating emissions than lab-reported data show, as per a recent analysis.

Growing Gap In Official and Actual Emissions

Data reveals that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a non-profit group. That contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined data from onboard energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” said a senior analyst involved in the report. “That discrepancy is growing and creates a serious problem. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery mode relative to total mileage. The team found that only a quarter of travel was completed in EV mode, while lab estimates assumed over four-fifths.

Even, when operating in EV mode, emission levels were well above lab estimates. That happened because electric motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled four large automaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 extra annually in operating costs than would be estimated under lab conditions.

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” commented a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Pressure

Hybrid vehicles have lately been drawn back into political discussions as carmakers have pressed the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large automotive manufacturing.

Several senior officials have proposed PHEVs as a possible “flexibility” option to introduce in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful addition” after years in which segments of the car industry argued there was insufficient information to accurately evaluate actual emissions.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or diesel cars,” they stated. “Any policy changes concerning PHEVs should be implemented with utmost care and in the light of this evidence.”