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PHEVs produce almost five times more planet-heating emissions than official data show, according to a new report.

Widening Gap In Official and Real-World Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit group. That differs sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a lead analyst involved in the report. “This discrepancy is growing and creates a serious problem. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power compared to total mileage. The team determined that only a quarter of travel was done in EV mode, whereas lab assumptions assumed over four-fifths.

Even, when running in electric mode, pollution amounts were well above official projections. This happened because electric motors were not strong sufficient to operate independently, leading to engines burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating costs than is assumed under lab tests.

“The bold statements that automakers like to make about their PHEV vehicles are obviously far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as automakers have lobbied 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 member states with significant automotive manufacturing.

Some high-level politicians have proposed PHEVs as a potential “flexibility” solution to include in the legislation.

One independent energy policy expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which parts of the automotive industry claimed there was too little data to accurately evaluate real-world emissions.

“The results show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme care and considering this data.”