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PHEVs emit nearly five times greater planet-heating pollution than lab-reported figures show, as per a new report.

Growing Gap In Official and Actual Emissions

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy organization. This differs significantly with lab tests, which suggested a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead analyst involved in the report. “This gap is growing and poses a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery power relative to total mileage. The team found that only a quarter of travel was completed in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution levels were significantly higher than lab projections. That happened because electric motors were insufficiently powerful enough to operate alone, resulting to combustion motors using gasoline for almost one-third of the travel covered in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more per year in operating costs than is assumed under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as carmakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large car industries.

Some high-level officials have suggested plug-in hybrids as a potential “compromise” option to include in the regulation.

An external energy economics expert, who was not involved with the study, described the report a “very useful contribution” after a long period in which segments of the car sector argued there was insufficient data to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert said. “All regulatory changes regarding PHEVs should be made with utmost caution and in the light of this data.”