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Plug-in hybrid cars release almost five times more planet-heating emissions than lab-reported data indicate, as per a new analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs emit only one-fifth less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy organization. This differs sharply with lab tests, which suggested a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” stated a senior researcher involved in the study. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode relative to overall mileage. They determined that just 27% of travel was completed in electric mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than official estimates. That happened because EV motors were not strong sufficient to function independently, resulting to combustion motors using gasoline for almost one-third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions allowed several major automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating costs than is estimated under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with large car manufacturing.

Some high-level officials have proposed plug-in hybrids as a possible “compromise” option to include in the legislation.

An independent energy policy specialist, who was unaffiliated with the study, called the report a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was too little information to accurately assess actual emissions.

“These findings show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel cars,” they stated. “All policy adjustments regarding PHEVs should be made with utmost caution and in the light of this evidence.”