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Plug-in hybrid electric vehicles produce nearly five times greater planet-heating emissions than official figures indicate, according to a new report.

Growing Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs emit only one-fifth lower CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit group. This differs sharply with laboratory tests, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” stated a senior researcher involved in the report. “This gap is growing and poses a significant issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Researchers linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery power relative to total mileage. They found that just 27% of driving was done in EV mode, whereas lab assumptions suggested over four-fifths.

Even, when running in electric mode, pollution amounts were well above lab projections. That happened because EV motors were not strong sufficient to function alone, resulting to engines using gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed several major carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

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

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been brought back into policy debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense lobbying from the car sector and opposition from member states with large car manufacturing.

Several high-level politicians have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

An external energy economics specialist, who was unaffiliated with the research, described the report a “very useful contribution” after years in which parts of the car sector argued there was too little information to properly evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme care and in the light of that data.”