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Plug-in hybrid electric vehicles release nearly 5x greater planet-heating emissions than lab-reported figures show, as per a new report.

Growing Discrepancy In Official and Real-World CO2 Output

Data shows that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. That contrasts sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts examined data from in-vehicle energy use meters of 800,000 cars registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a senior researcher participating in the report. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in battery power compared to overall distance. The team found that just 27% of travel was completed in EV mode, whereas official estimates assumed over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than official projections. That occurred because EV motors were not strong enough to operate alone, resulting to combustion motors using gasoline for nearly a third of the distance covered in EV mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV emissions allowed several major automaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating expenses than would be estimated under lab conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought again into policy debates as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with large automotive industries.

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

An external energy policy specialist, who was not involved with the study, described the analysis a “very useful addition” after years in which parts of the automotive industry claimed there was insufficient data to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the difference between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” they stated. “Any regulatory changes concerning PHEVs should be implemented with utmost care and in the light of this data.”