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Plug-in hybrid cars emit nearly 5x greater global warming emissions than official data indicate, as per a recent report.

Growing Gap Between Official and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy group. This differs sharply with lab tests, which assumed a three-quarters decrease in emissions.

Analysts examined data from onboard fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” stated a senior researcher participating in the study. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode compared to overall distance. They found that just a quarter of driving was completed in electric mode, while lab estimates suggested 84%.

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

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output allowed four large carmaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more annually in operating costs than is estimated under lab tests.

“The strong statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Hybrid vehicles have lately been drawn back into policy discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive industry and opposition from member states with significant car industries.

Several high-level officials have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An external energy policy specialist, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was insufficient data to properly assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” they said. “Any policy adjustments regarding PHEVs should be made with utmost caution and considering this data.”