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Plug-in hybrid electric vehicles release almost five times greater global warming pollution than official figures indicate, as per a new analysis.

Growing Gap Between Lab and Real-World Emissions

Statistics shows that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit organization. This differs significantly with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers studied information from onboard fuel consumption meters of 800,000 cars registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” stated a lead analyst involved in the report. “That gap is growing and creates a serious problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to overall mileage. They determined that only 27% of travel was completed in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when running in EV mode, emission levels were well above official projections. That occurred because electric motors were not strong enough to operate alone, leading to engines burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions allowed several large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in running costs than is estimated under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought again into political discussions as carmakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant automotive industries.

Several high-level politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which parts of the car industry argued there was insufficient information to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost caution and considering that evidence.”