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PHEVs release nearly five times more global warming emissions than lab-reported data show, according to a new analysis.

Widening Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a non-profit group. This contrasts sharply with lab tests, which assumed a three-quarters reduction in pollution.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a senior researcher involved in the study. “That discrepancy is growing and creates a significant issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode relative to total distance. The team determined that only 27% of driving was completed in electric mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV emissions allowed several major carmaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

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

“The strong claims that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Political Discussion and Industry Pressure

Hybrid vehicles have lately been drawn again into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with large automotive manufacturing.

Some high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the regulation.

An external energy policy specialist, who was not involved with the study, called the analysis a “very useful contribution” after years in which segments of the car industry argued there was insufficient information to accurately assess actual emissions.

“The results show, without question, that the difference between official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert said. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that data.”