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Plug-in hybrid cars produce nearly five times greater planet-heating emissions than official data show, according to a new report.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy organization. This differs sharply with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a lead researcher participating in the study. “This gap is growing and poses a significant problem. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to total distance. They determined that only 27% of driving was done in electric mode, while official assumptions suggested 84%.

Additionally, when running in EV mode, emission amounts were well above official estimates. That happened because EV motors were not strong enough to operate alone, leading to engines burning fossil fuels for almost a third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to estimates, the underestimation of PHEV CO2 output enabled four major carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more per year in running expenses than is assumed under laboratory conditions.

“The strong statements that automakers often promote about their PHEV cars are clearly far from the mark,” stated a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been brought again into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the car sector and opposition from member states with significant car manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the study, called the report a “highly valuable addition” after a long period in which parts of the car industry claimed there was insufficient data to accurately assess actual emissions.

“These findings show, beyond any doubt, that the gap in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and considering that data.”