🔗 Share this article

Plug-in hybrid electric vehicles emit nearly five times greater planet-heating pollution than lab-reported figures indicate, as per a new analysis.

Widening Gap Between Lab and Real-World Emissions

Data reveals that PHEVs release only 19% lower CO₂ than traditional petrol and diesel cars, according to research carried out by a advocacy organization. This differs sharply with lab tests, which assumed a three-quarters decrease in emissions.

Analysts studied data from onboard energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a lead analyst participating in the study. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Researchers linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in electric mode compared to total distance. The team determined that only a quarter of driving was done in EV mode, whereas official estimates assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were not strong sufficient to function alone, leading to engines using gasoline for nearly one-third of the travel covered in EV mode.

Policy and Economic Implications

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

Additionally, owners of PHEVs would spend about €500 more per year in running costs than is estimated under lab tests.

“The strong statements that automakers often promote about their PHEV cars are obviously far from the mark,” stated a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been drawn back into political debates as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive industries.

Several senior officials have suggested PHEVs as a possible “flexibility” option to include in the legislation.

An external energy economics expert, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the car sector argued there was insufficient data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with extreme caution and considering that evidence.”