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PHEVs emit almost five times greater global warming emissions than official figures indicate, according to a recent analysis.

Growing Discrepancy In Lab and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, according to analysis carried out by a non-profit organization. That differs sharply with lab estimates, which suggested a 75% reduction in emissions.

Researchers studied information from in-vehicle energy use meters of 800,000 cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a senior researcher involved in the study. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric mode compared to total distance. The team found that only 27% of driving was completed in electric mode, whereas official assumptions assumed 84%.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. This happened because EV motors were not strong enough to operate independently, leading to combustion motors burning gasoline for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled several large carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could spend about €500 extra per year in running expenses than is estimated under laboratory tests.

“The bold statements that automakers often promote about their PHEV cars are clearly way off the mark,” stated a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been brought again into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and resistance from member states with significant automotive manufacturing.

Several high-level politicians have proposed PHEVs as a possible “flexibility” option to introduce in the regulation.

One external energy economics expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which segments of the automotive industry argued there was too little information to accurately assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for petrol or diesel vehicles,” they said. “All regulatory adjustments concerning PHEVs should be made with extreme caution and considering that data.”