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Plug-in hybrid cars produce nearly five times more planet-heating pollution than lab-reported data indicate, as per a recent analysis.

Growing Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a advocacy group. That differs sharply with laboratory tests, which suggested a three-quarters decrease in emissions.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” stated a lead analyst participating in the study. “That gap is widening and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery mode relative to overall distance. The team determined that just 27% of driving was done in EV mode, whereas lab assumptions assumed 84%.

Additionally, when operating in EV mode, emission levels were well above lab estimates. That occurred because EV motors were insufficiently powerful sufficient to function alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled four major automaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 extra annually in running expenses than would be estimated under lab tests.

“The bold statements that automakers like to make about their PHEV vehicles are clearly far from the truth,” stated a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Hybrid vehicles have recently been brought again into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large automotive industries.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, called the report a “very useful contribution” after years in which parts of the automotive industry argued there was too little information to properly evaluate real-world emissions.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with utmost caution and considering this data.”