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Plug-in hybrid electric vehicles produce nearly five times greater planet-heating pollution than official figures indicate, according to a recent analysis.

Growing Gap Between Official and Actual Emissions

Statistics reveals that PHEVs emit only one-fifth less CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy group. That differs significantly with lab tests, which suggested a 75% decrease in emissions.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher participating in the report. “That gap is growing and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode compared to overall mileage. They found that only a quarter of driving was done in EV mode, while official assumptions assumed 84%.

Additionally, when operating in EV mode, emission amounts were significantly higher than official estimates. That happened because electric motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output enabled four major carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra per year in running expenses than is estimated under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly 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 cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have recently been brought back into political debates as automakers have pressed the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the car industry and opposition from member states with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

One external energy economics specialist, who was not involved with the research, called the report a “highly valuable contribution” after years in which segments of the car industry claimed there was insufficient information to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for petrol or diesel vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of this data.”