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PHEVs release almost five times more planet-heating emissions than official figures indicate, according to a new analysis.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a non-profit group. That differs significantly with lab estimates, which suggested a 75% reduction in pollution.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are falling,” said a senior researcher involved in the report. “This gap is widening and creates a serious problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery power compared to overall distance. The team found that only 27% of driving was done in electric mode, while lab estimates assumed over four-fifths.

Additionally, when operating in electric mode, emission levels were significantly higher than lab projections. This happened because EV motors were insufficiently powerful enough to function alone, leading to combustion motors burning fossil fuels for almost a third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled several major carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend about €500 extra annually in running costs than is estimated under laboratory tests.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as automakers have pressed the European Union to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the car sector and resistance from member states with large automotive manufacturing.

Some senior officials have proposed plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An independent energy policy specialist, who was not involved with the study, called the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was insufficient data to accurately assess actual emissions.

“These findings demonstrate, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or conventional vehicles,” they stated. “All regulatory changes regarding PHEVs should be implemented with extreme caution and considering this data.”