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Plug-in hybrid electric vehicles produce nearly 5x more global warming emissions than lab-reported figures show, as per a new analysis.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs release just one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis carried out by a advocacy group. That differs significantly with lab tests, which assumed a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles registered 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 three and a half times in 2021.

“Actual CO2 output are rising, while official figures are falling,” stated a senior researcher involved in the study. “This gap is growing and creates a serious problem. Consequently, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to total mileage. They determined that only 27% of driving was completed in electric mode, while official assumptions assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above official estimates. That occurred because electric motors were not strong enough to operate alone, resulting to engines using fossil fuels for almost a third of the travel covered in electric mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output allowed several major automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in operating expenses than is estimated under laboratory tests.

“The bold claims that automakers like to make about their PHEV cars are clearly far from the mark,” commented a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have lately been brought again into policy discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from EU countries with significant car manufacturing.

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

An independent energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after years in which parts of the automotive sector argued there was too little data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert said. “Any policy changes regarding PHEVs should be implemented with extreme care and considering this evidence.”