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PHEVs produce almost five times more global warming pollution than lab-reported figures show, according to a recent analysis.

Widening Gap Between Official and Real-World Emissions

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel cars, based on research carried out by a non-profit group. This differs significantly with lab tests, which assumed a 75% decrease in emissions.

Analysts examined data from onboard energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a senior analyst involved in the study. “That gap is widening and creates a significant issue. Consequently, PHEVs emit almost as much as petrol cars.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric power compared to total distance. The team found that just 27% of travel was done in EV mode, while official estimates suggested 84%.

Additionally, when operating in electric mode, pollution levels were well above lab projections. This happened because electric motors were not strong enough to operate independently, leading to combustion motors burning fossil fuels for nearly a third of the travel completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV emissions enabled several large carmaker groups to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 more annually in operating expenses than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have recently been brought again into policy debates as automakers have pressed the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from member states with significant automotive manufacturing.

Some high-level politicians have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One external energy policy specialist, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little information to properly assess actual emissions.

“The results show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be made with utmost caution and in the light of this data.”