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PHEVs produce nearly 5x greater planet-heating emissions than lab-reported figures indicate, as per a new analysis.

Widening Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. This differs sharply with lab tests, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a senior analyst participating in the report. “This gap is growing and poses a serious issue. Consequently, PHEVs emit almost as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric mode compared to total distance. The team determined that just a quarter of travel was completed in EV mode, while official assumptions suggested 84%.

Additionally, when running in electric mode, emission levels were well above official estimates. This occurred because EV motors were not strong enough to operate alone, leading to engines burning fossil fuels for nearly one-third of the distance completed in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed four major automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in running expenses than is estimated under laboratory tests.

“The bold claims that automakers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little improved than regular gas and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Political Debate and Industry Lobbying

Hybrid vehicles have recently been drawn back into political discussions as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with significant car manufacturing.

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

One external energy policy specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which parts of the automotive sector argued there was too little data to properly assess actual CO2 output.

“The results show, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost care and in the light of that data.”