Plug-in Hybrid Cars Emit Almost as Heavily as Petrol Vehicles, Study Finds

Plug-in hybrid electric vehicles produce nearly five times greater global warming pollution than lab-reported data show, according to a recent analysis.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit group. That differs significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers studied information from onboard fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” stated a senior analyst involved in the report. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power compared to total mileage. They determined that only 27% of driving was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above official projections. This occurred because electric motors were not strong sufficient to function independently, resulting to engines using gasoline for almost a third of the distance covered in EV mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 more per year in running expenses than is assumed under lab tests.

“The bold statements that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy debates as carmakers have pressed the EU to relax CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from member states with significant car industries.

Some senior politicians have suggested PHEVs as a potential “flexibility” option to include in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which parts of the automotive sector argued there was too little data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional cars,” they stated. “Any policy adjustments regarding PHEVs should be made with extreme caution and in the light of that data.”