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PHEVs release nearly five times more global warming emissions than lab-reported figures show, according to a new analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on research carried out by a advocacy group. That contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 cars registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a senior analyst participating in the study. “That discrepancy is widening and creates a significant issue. As a result, PHEVs emit almost as heavily as gasoline cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in battery mode relative to total mileage. They found that just a quarter of driving was done in electric mode, whereas lab assumptions assumed 84%.

Even, when operating in EV mode, emission levels were well above official projections. That happened because EV motors were not strong sufficient to function independently, leading to combustion motors burning fossil fuels for nearly one-third of the distance completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed several major automaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend approximately €500 more per year in operating costs than would be estimated under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with significant automotive industries.

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

One external energy economics expert, who was unaffiliated with the research, described the analysis a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was insufficient information to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference between 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 regarding PHEVs should be implemented with utmost care and in the light of this data.”