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PHEVs produce almost five times greater planet-heating emissions than lab-reported data indicate, as per a new analysis.

Growing Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, based on analysis carried out by a advocacy group. This contrasts sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Researchers studied data from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” stated a senior analyst participating in the report. “This discrepancy is widening and poses a significant problem. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode compared to overall distance. The team determined that only a quarter of driving was completed in electric mode, while lab estimates suggested 84%.

Even, when operating in electric mode, emission levels were well above lab projections. This occurred because EV motors were insufficiently powerful enough to function independently, resulting to engines burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV emissions enabled four major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in operating costs than would be assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV cars are clearly far from the mark,” commented a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have pressed the European Union to weaken CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from EU countries with significant automotive manufacturing.

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

An independent energy economics expert, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which parts of the car sector claimed there was too little information to properly assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they said. “Any regulatory changes regarding PHEVs should be made with utmost care and considering this evidence.”