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PHEVs release nearly five times greater planet-heating pollution than lab-reported figures indicate, according to a new report.

Growing Gap In Official and Real-World Emissions

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit organization. This contrasts sharply with lab tests, which assumed a 75% decrease in pollution.

Analysts studied information from onboard energy use meters of 800,000 cars sold 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 figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a lead researcher involved in the study. “This gap is growing and creates a significant problem. Consequently, PHEVs emit almost as much as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power compared to total mileage. They found that only a quarter of driving was completed in electric mode, while lab assumptions assumed 84%.

Additionally, when running in electric mode, emission levels were well above official projections. That happened because EV motors were not strong sufficient to function independently, resulting to combustion motors using fossil fuels for nearly a third of the travel completed in electric mode.

Policy and Financial Consequences

According to estimates, the underestimation of PHEV emissions allowed several large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in operating expenses than would be assumed under laboratory tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have recently been drawn back into political discussions as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car industries.

Some high-level officials have suggested plug-in hybrids as a potential “flexibility” option to introduce in the legislation.

One external energy policy specialist, who was not involved with the research, called the analysis a “highly valuable addition” after years in which segments of the car industry claimed there was insufficient data to properly evaluate real-world emissions.

“These findings demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert said. “Any policy changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”