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PHEVs produce nearly 5x more global warming emissions than official figures show, according to a new report.

Growing Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit group. This contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Researchers examined information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” stated a lead researcher involved in the report. “This gap is widening and poses a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in battery power relative to overall mileage. The team determined that only a quarter of travel was done in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in electric mode, emission levels were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to operate alone, resulting to engines using fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled four major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 extra per year in running expenses than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Political Discussion and Industry Pressure

Hybrid vehicles have recently been brought back into policy debates as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car industry and resistance from member states with significant automotive manufacturing.

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

An external energy economics expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was too little data to accurately evaluate real-world emissions.

“These findings show, without question, that the difference between lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and in the light of that data.”