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Plug-in hybrid electric vehicles produce almost five times greater global warming emissions than official figures show, according to a recent analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy group. That contrasts significantly with laboratory tests, which suggested a three-quarters decrease in pollution.

Researchers examined information from in-vehicle fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a senior analyst participating in the report. “This gap is widening and creates a serious problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric mode relative to total mileage. They found that only a quarter of travel was done in EV mode, whereas lab estimates assumed 84%.

Even, when running in EV mode, emission levels were well above lab projections. That happened because electric motors were not strong sufficient to function independently, resulting to combustion motors burning gasoline for nearly one-third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled several major automaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 more per year in running costs than would be assumed under laboratory conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been brought again into policy discussions as automakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant automotive manufacturing.

Several high-level politicians have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after years in which parts of the car sector claimed there was too little data to accurately evaluate real-world emissions.

“The results show, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and in the light of this evidence.”