🔗 Share this article

Plug-in hybrid electric vehicles emit nearly 5x greater global warming emissions than official figures show, according to a recent report.

Widening Gap In Official and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit organization. This differs sharply with laboratory estimates, which suggested a 75% decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a senior researcher involved in the report. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Researchers linked most of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to overall distance. They found that only a quarter of driving was completed in EV mode, while lab assumptions assumed over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab projections. This happened because EV motors were insufficiently powerful enough to function alone, leading to engines burning gasoline for nearly a third of the distance completed in electric mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV CO2 output allowed four large automaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra per year in running costs than would be assumed under lab tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously far from the mark,” stated a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with large car industries.

Several senior politicians have suggested PHEVs as a potential “flexibility” option to introduce in the legislation.

An external energy economics expert, who was not involved with the study, called the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was insufficient data to properly assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” the expert said. “Any policy adjustments concerning PHEVs should be implemented with utmost care and considering that data.”