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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating pollution than official data show, according to a recent analysis.

Growing Gap Between Official and Real-World Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy group. That differs significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers examined information from in-vehicle fuel consumption meters of eight hundred thousand cars sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” stated a senior researcher involved in the study. “That gap is widening and creates a serious issue. As a result, PHEVs emit almost as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to overall distance. The team found that just a quarter of driving was done in electric mode, while lab assumptions assumed over four-fifths.

Even, when running in EV mode, emission amounts were well above official projections. That happened because EV motors were not strong enough to operate alone, resulting to engines burning fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV CO2 output enabled four major automaker companies to escape over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra annually in running expenses than is estimated under laboratory tests.

“The strong claims that automakers like to make about their PHEV vehicles are clearly way off the mark,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have recently been drawn back into policy debates as automakers have pressed the European Union to relax CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with significant automotive industries.

Some senior officials have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

An external energy economics 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 data to properly assess real-world CO2 output.

“These findings show, without question, that the difference between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”