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Plug-in hybrid electric vehicles release almost 5x more planet-heating emissions than official data show, according to a recent analysis.

Growing Discrepancy Between Official and Actual CO2 Output

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit organization. That contrasts sharply with lab tests, which assumed a 75% reduction in pollution.

Analysts examined information from onboard energy use meters of 800,000 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 estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” stated a senior analyst participating in the report. “That gap is widening and creates a significant issue. Consequently, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery power compared to total distance. They found that only a quarter of travel was completed in electric mode, whereas official assumptions suggested 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than official projections. That happened because electric motors were not strong sufficient to operate alone, leading to engines burning gasoline for almost one-third of the distance completed in EV mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output enabled four major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are obviously way off the truth,” stated a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid cars have recently been drawn back into policy discussions as automakers have pressed the European Union to weaken CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with large car manufacturing.

Several senior officials have proposed PHEVs as a potential “compromise” solution to include in the regulation.

One external energy policy expert, who was unaffiliated with the study, described the analysis a “very useful contribution” after years in which parts of the automotive sector claimed there was insufficient information to properly assess real-world CO2 output.

“These findings show, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional cars,” the expert said. “All policy adjustments regarding PHEVs should be made with utmost care and in the light of this data.”