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PHEVs release nearly five times more planet-heating emissions than official data indicate, according to a recent report.

Growing Gap Between Official and Real-World Emissions

Data reveals that PHEVs release just 19% less CO₂ than conventional gas and diesel vehicles, according to research conducted by a non-profit organization. That contrasts significantly with laboratory tests, which suggested a 75% reduction in pollution.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “This gap is widening and poses a serious problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to overall mileage. They found that just 27% of driving was done in electric mode, while official assumptions assumed over four-fifths.

Additionally, when running in electric mode, emission levels were well above lab estimates. That happened because electric motors were insufficiently powerful enough to function alone, resulting to engines burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions enabled four major automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 extra annually in running expenses than would be assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV vehicles are obviously way off the truth,” commented a automotive expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with large automotive industries.

Several senior politicians have proposed PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy policy specialist, who was not involved with the study, called the analysis a “very useful addition” after a long period in which segments of the automotive industry argued there was too little data to accurately assess actual emissions.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or conventional vehicles,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and considering that data.”