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Plug-in hybrid cars emit nearly five times greater global warming emissions than lab-reported figures indicate, as per a recent report.

Widening Discrepancy In Official and Real-World CO2 Output

Data reveals that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a advocacy group. This contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a lead analyst involved in the study. “This discrepancy is growing and poses a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles driven in electric power compared to overall mileage. They found that only 27% of driving was done in electric mode, whereas lab assumptions assumed over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than lab projections. This occurred because electric motors were not strong sufficient to function independently, leading to combustion motors using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV emissions allowed several major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in running costs than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into political debates as carmakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with significant automotive manufacturing.

Several senior officials have proposed PHEVs as a possible “compromise” option to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the research, described the analysis a “very useful addition” after years in which segments of the automotive sector argued there was too little information to properly assess actual emissions.

“These findings show, without question, that the difference in lab and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”