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PHEVs release nearly 5x more global warming emissions than official figures indicate, according to a new analysis.

Widening Gap In Official and Actual Emissions

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit organization. This differs significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” stated a senior analyst involved in the study. “This gap is widening and creates a significant issue. Consequently, PHEVs emit almost as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to total distance. They determined that only 27% of travel was done in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were significantly higher than lab estimates. This occurred because EV motors were not strong sufficient to operate independently, leading to engines burning fossil fuels for nearly one-third of the travel covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four major carmaker companies to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in running costs than is assumed under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into policy debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with significant car manufacturing.

Some senior politicians have suggested PHEVs as a potential “flexibility” option to include in the regulation.

An external energy policy specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the automotive sector claimed there was too little information to properly assess actual emissions.

“These findings demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel cars,” the expert said. “All regulatory adjustments regarding PHEVs should be implemented with extreme care and in the light of this data.”