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Plug-in hybrid electric vehicles release nearly 5x more planet-heating emissions than lab-reported figures show, according to a new analysis.

Growing Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs release only 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. That contrasts significantly with lab tests, which assumed a 75% reduction in emissions.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are falling,” said a senior analyst involved in the study. “This gap is growing and poses a significant problem. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in battery mode compared to overall distance. They determined that only 27% of travel was completed in electric mode, whereas lab estimates assumed over four-fifths.

Additionally, when operating in EV mode, emission levels were well above lab projections. That happened because electric motors were not strong sufficient to function independently, resulting to combustion motors burning gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in operating expenses than is assumed under lab tests.

“The strong claims that automakers like to make about their plug-in hybrid cars are obviously far from the truth,” stated a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from member states with large car manufacturing.

Several senior officials have proposed plug-in hybrids as a potential “flexibility” option to include in the legislation.

An independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which segments of the automotive industry argued there was insufficient information to accurately evaluate real-world emissions.

“The results show, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with utmost care and considering this evidence.”