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PHEVs produce nearly 5x greater global warming pollution than lab-reported data indicate, according to a recent analysis.

Growing Gap Between Official and Actual Emissions

Statistics shows that PHEVs emit only 19% less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a non-profit group. That differs sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead analyst participating in the report. “This discrepancy is growing and poses a serious issue. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in battery mode compared to total mileage. The team found that just 27% of driving was completed in electric mode, whereas official assumptions assumed over four-fifths.

Even, when running in EV mode, emission amounts were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to function alone, leading to engines burning fossil fuels for nearly a third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several major automaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 extra per year in operating expenses than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously far from the mark,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into policy debates as carmakers have pressed the European Union to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with large car industries.

Some senior officials have proposed plug-in hybrids as a potential “flexibility” option to introduce in the legislation.

An independent energy economics expert, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the car sector argued there was insufficient information to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel cars,” they said. “All policy changes regarding PHEVs should be implemented with utmost care and considering this data.”