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Plug-in hybrid cars emit almost five times more global warming emissions than lab-reported data indicate, according to a new analysis.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on analysis carried out by a non-profit group. This differs significantly with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 vehicles registered in the EU between 2021 and 2023. The team discovered that actual 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 official figures are decreasing,” stated a senior researcher involved in the report. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs emit almost as much as petrol vehicles.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode compared to overall mileage. They found that only a quarter of travel was completed in EV mode, while official assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were significantly higher than lab projections. This occurred because electric motors were not strong enough to operate alone, resulting to engines using fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions allowed four major automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 extra annually in running expenses than would be estimated under lab conditions.

“The bold statements that automakers like to make about their PHEV vehicles are clearly way off the truth,” stated a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant automotive industries.

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

One external energy policy expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which segments of the automotive sector argued there was insufficient information to properly assess actual CO2 output.

“The results demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with extreme care and in the light of that evidence.”