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Plug-in hybrid electric vehicles produce nearly five times greater planet-heating emissions than official figures indicate, as per a recent analysis.

Growing Discrepancy In Official and Real-World Emissions

Data reveals that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy organization. That differs sharply with laboratory tests, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard energy use meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a senior researcher involved in the study. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked the majority of the gap to overestimates of the “utility factor” – the ratio of miles travelled in electric power compared to overall distance. They determined that only a quarter of travel was done in electric mode, while lab estimates suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That happened because EV motors were not strong enough to function independently, leading to combustion motors using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four large automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more per year in running expenses than would be estimated under laboratory tests.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as carmakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from member states with large car manufacturing.

Several high-level officials have suggested PHEVs as a possible “flexibility” option to include in the regulation.

An external energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which segments of the automotive sector argued there was too little data to accurately evaluate real-world emissions.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and in the light of this data.”