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Plug-in hybrid electric vehicles release nearly five times more planet-heating emissions than official data show, as per a new report.

Widening Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy organization. This contrasts significantly with laboratory tests, which assumed a 75% decrease in pollution.

Researchers studied data from in-vehicle energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” stated a lead researcher involved in the study. “That gap is growing and creates a serious issue. Consequently, PHEVs emit almost as much as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery mode compared to overall mileage. They determined that just 27% of travel was done in electric mode, while official estimates suggested over four-fifths.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab projections. That occurred because EV motors were insufficiently powerful enough to operate alone, leading to engines using fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 extra annually in operating expenses than is assumed under laboratory tests.

“The bold statements that automakers often promote about their PHEV vehicles are clearly way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have recently been drawn again into policy debates as automakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with large car industries.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

One external energy economics specialist, who was not involved with the study, called the analysis a “very useful contribution” after years in which parts of the car industry argued there was insufficient data to properly assess actual emissions.

“The results demonstrate, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert said. “Any regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of that data.”