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Plug-in hybrid cars produce nearly five times greater global warming emissions than lab-reported data indicate, according to a recent report.

Growing Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs release just one-fifth less CO₂ than conventional gas and diesel cars, based on research carried out by a advocacy organization. That differs sharply with lab tests, which suggested a 75% reduction in emissions.

Analysts examined data from onboard energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “That gap is widening and creates a serious problem. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to total distance. The team found that only a quarter of driving was completed in electric mode, whereas official estimates suggested 84%.

Even, when running in EV mode, pollution levels were significantly higher than official estimates. That occurred because EV motors were not strong enough to operate independently, resulting to engines using fossil fuels for almost one-third of the travel covered in electric mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled several large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend about €500 more annually in operating costs than is estimated under laboratory tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Hybrid cars have recently been drawn again into policy debates as automakers have pressed the EU to weaken CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive industries.

Some senior politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful addition” after years in which segments of the automotive industry claimed there was too little information to accurately evaluate actual CO2 output.

“These findings demonstrate, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they said. “All policy changes concerning PHEVs should be made with utmost care and in the light of that evidence.”