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Plug-in hybrid electric vehicles release nearly five times more planet-heating emissions than lab-reported figures indicate, as per a new analysis.

Widening Gap In Official and Actual CO2 Output

Data reveals that PHEVs release only 19% lower CO₂ than conventional gas and diesel cars, based on research carried out by a non-profit organization. That contrasts sharply with lab estimates, which suggested a 75% reduction in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” stated a lead analyst involved in the study. “This gap is widening and poses a serious issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery power relative to overall distance. They found that only a quarter of driving was done in electric mode, while official assumptions assumed 84%.

Additionally, when operating in electric mode, emission levels were well above official projections. That happened because electric motors were not strong sufficient to function independently, resulting to engines using fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed several major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 extra annually in operating expenses than would be estimated under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV cars are obviously way off the truth,” stated a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large car manufacturing.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An independent energy policy expert, who was unaffiliated with the research, described the report a “highly valuable addition” after years in which segments of the car industry claimed there was insufficient information to accurately assess actual emissions.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “Any policy changes concerning PHEVs should be implemented with extreme caution and considering that evidence.”