Plug in Hybrid Cars Pollute Nearly as Much as Petrol Cars, Study Reveals

Plug-in hybrid electric vehicles release almost five times more planet-heating emissions than lab-reported data indicate, according to a new report.

Growing Discrepancy Between Lab and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit organization. That contrasts sharply with lab tests, which suggested a 75% decrease in pollution.

Researchers studied information from onboard fuel consumption meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are falling,” stated a lead researcher involved in the report. “This discrepancy is growing and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Factors Driving the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode compared to overall distance. The team found that only a quarter of travel was done in EV mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, emission amounts were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful enough to function alone, leading to engines burning gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled four major automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 more per year in operating costs than would be assumed under laboratory conditions.

“The strong statements that manufacturers often promote about their PHEV cars are obviously way off the truth,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into political discussions as automakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the car sector and resistance from member states with significant car industries.

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

One independent energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after years in which segments of the automotive sector argued there was insufficient information to properly assess actual CO2 output.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and considering that evidence.”