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Plug-in hybrid cars produce almost five times greater planet-heating emissions than official figures indicate, as per a new analysis.

Growing Discrepancy In Official and Actual CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, based on research conducted by a non-profit organization. That differs significantly with lab tests, which suggested a 75% reduction in emissions.

Researchers examined data from onboard energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a lead analyst involved in the study. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery mode relative to total mileage. The team found that just 27% of travel was completed in EV mode, whereas lab assumptions assumed 84%.

Even, when operating in electric mode, emission amounts were significantly higher than official estimates. This occurred because electric motors were not strong enough to function independently, leading to combustion motors using gasoline for almost a third of the distance completed in electric mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output enabled four large automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in running expenses than is estimated under lab tests.

“The strong claims that automakers often promote about their PHEV cars are obviously way off the mark,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into political discussions as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large car manufacturing.

Some senior politicians have proposed PHEVs as a possible “compromise” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, described the report a “highly valuable addition” after a long period in which parts of the car sector claimed there was insufficient data to properly assess real-world emissions.

“These findings show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert said. “All regulatory changes regarding PHEVs should be implemented with utmost care and in the light of that data.”