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Plug-in hybrid electric vehicles produce almost 5x greater global warming pollution than lab-reported figures indicate, according to a recent report.

Widening Discrepancy In Official and Actual CO2 Output

Statistics shows that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a advocacy organization. That differs significantly with lab estimates, which assumed a 75% reduction in emissions.

Researchers examined information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a lead researcher involved in the study. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power compared to overall distance. They found that only 27% of driving was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission levels were significantly higher than lab estimates. That occurred because EV motors were not strong enough to operate independently, resulting to engines using gasoline for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV emissions allowed several major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 more annually in operating expenses than is assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV cars are obviously way off the truth,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Hybrid vehicles have recently been brought again into political debates as carmakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced intense lobbying from the car industry and opposition from member states with large car manufacturing.

Several senior officials have proposed plug-in hybrids as a possible “flexibility” option to include in the legislation.

An external energy policy specialist, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which segments of the automotive sector claimed there was too little data to properly assess actual emissions.

“The results demonstrate, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be made with utmost caution and in the light of that data.”