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Plug-in hybrid electric vehicles produce almost five times more planet-heating pollution than official data show, as per a recent analysis.

Widening Discrepancy Between Official and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a three-quarters reduction in emissions.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a lead researcher involved in the study. “This discrepancy is growing and creates a serious problem. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Analysts linked most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in electric power relative to overall distance. The team determined that just a quarter of driving was completed in electric mode, whereas lab assumptions assumed 84%.

Additionally, when operating in EV mode, emission levels were significantly higher than lab estimates. That occurred because electric motors were not strong sufficient to operate alone, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 more per year in operating costs than would be assumed under laboratory tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the truth,” stated a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy debates as carmakers have pressed the EU to relax CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

An independent energy policy expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was too little information to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost caution and in the light of this evidence.”