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Plug-in hybrid electric vehicles produce nearly five times greater planet-heating pollution than official data indicate, according to a recent report.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a advocacy organization. That differs significantly with lab tests, which suggested a 75% decrease in emissions.

Analysts examined information from onboard fuel consumption monitors of 800,000 cars sold in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a senior analyst involved in the study. “That gap is growing and poses a serious problem. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in electric mode relative to overall distance. The team found that only a quarter of travel was done in electric mode, whereas lab estimates suggested 84%.

Even, when operating in EV mode, emission amounts were well above official estimates. This happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV CO2 output allowed several major automaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 more annually in operating expenses than would be assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously way off the truth,” stated a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought back into policy discussions as automakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with significant automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful addition” after years in which parts of the car sector claimed there was too little information to accurately assess real-world CO2 output.

“The results show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert said. “Any regulatory changes concerning PHEVs should be made with utmost care and considering that data.”