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Plug-in hybrid cars emit almost five times greater global warming emissions than official data indicate, as per a new analysis.

Growing Discrepancy In Lab and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit organization. This differs sharply with lab tests, which suggested a 75% decrease in pollution.

Analysts examined information from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” stated a senior analyst participating in the report. “This discrepancy is widening and creates a significant problem. Consequently, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to total distance. They determined that just a quarter of driving was completed in electric mode, while official estimates assumed 84%.

Even, when running in electric mode, emission amounts were well above official projections. This happened because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors burning fossil fuels for almost a third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in operating costs than is estimated under laboratory conditions.

“The strong statements that automakers often promote about their plug-in hybrid cars are clearly way off the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Hybrid vehicles have lately been brought again into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the car sector and resistance from EU countries with large automotive industries.

Some senior officials have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the car industry argued there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel cars,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme care and in the light of this data.”