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Plug-in hybrid electric vehicles release almost five times greater planet-heating emissions than official figures indicate, as per a new report.

Widening Discrepancy In Official and Real-World Emissions

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit group. That contrasts significantly with lab estimates, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher participating in the study. “This gap is growing and poses a serious issue. Consequently, PHEVs emit almost as much as petrol cars.”

Primary Reasons Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in electric mode compared to overall distance. The team determined that just a quarter of driving was completed in EV mode, while lab estimates assumed over four-fifths.

Even, when operating in EV mode, emission levels were well above official estimates. This occurred because electric motors were not strong enough to function alone, resulting to combustion motors using gasoline for nearly one-third of the travel covered in electric mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV emissions enabled four major automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

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

“The bold claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn again into policy discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from EU countries with large automotive manufacturing.

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

One external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which parts of the car sector claimed there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be implemented with extreme care and considering this data.”