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PHEVs emit nearly five times greater global warming emissions than official data show, according to a recent report.

Growing Gap In Official and Real-World CO2 Output

Data reveals that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a advocacy group. This differs significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard energy use meters of 800,000 cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” stated a lead analyst involved in the report. “That gap is widening and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery power compared to total mileage. They determined that just 27% of driving was completed in electric mode, whereas official estimates suggested 84%.

Additionally, when running in electric mode, emission amounts were well above official estimates. This happened because EV motors were not strong sufficient to function alone, resulting to engines using gasoline for almost a third of the travel covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV emissions enabled several major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 more per year in running expenses than would be estimated under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large car manufacturing.

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

One independent energy economics expert, who was not involved with the study, called the report a “highly valuable addition” after a long period in which parts of the car industry argued there was insufficient data to accurately evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be made with extreme care and in the light of that data.”