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Plug-in hybrid electric vehicles produce almost five times more planet-heating emissions than lab-reported figures indicate, as per a recent report.

Widening Discrepancy In Official and Actual Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit group. This contrasts significantly with laboratory tests, which assumed a 75% decrease in emissions.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a lead analyst participating in the study. “That gap is growing and creates a serious problem. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to total mileage. The team determined that only a quarter of driving was done in EV mode, whereas official estimates suggested over four-fifths.

Even, when running in EV mode, pollution amounts were well above lab projections. This occurred because electric motors were not strong enough to operate independently, resulting to engines using gasoline for almost one-third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled several major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 extra annually in running costs than would be estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” commented a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large automotive industries.

Several high-level officials have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

One independent energy policy expert, who was not involved with the research, described the report a “highly valuable addition” after a long period in which segments of the automotive sector argued there was insufficient information to accurately assess actual emissions.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be made with extreme caution and considering this evidence.”