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Plug-in hybrid electric vehicles release almost five times more global warming pollution than official data show, as per a recent report.

Widening Discrepancy Between Official and Actual Emissions

Data shows that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a advocacy group. This contrasts sharply with laboratory estimates, which suggested a 75% reduction in pollution.

Researchers examined data from onboard energy use meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “This discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Primary Factors Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of miles driven in electric mode relative to overall distance. The team found that just a quarter of travel was done in EV mode, whereas lab assumptions assumed 84%.

Even, when operating in EV mode, emission amounts were well above lab estimates. This occurred because electric motors were insufficiently powerful enough to function independently, leading to combustion motors burning fossil fuels for almost a third of the travel covered in electric mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in running costs than is estimated under lab tests.

“The strong statements that automakers like to make about their PHEV vehicles are clearly way off the mark,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into policy debates as automakers have lobbied the European Union to relax CO₂ targets. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large car manufacturing.

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

An independent energy economics specialist, who was unaffiliated with the study, described the analysis a “very useful contribution” after years in which segments of the car sector argued there was too little data to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” they stated. “All regulatory changes concerning PHEVs should be implemented with utmost caution and considering that data.”