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Plug-in hybrid electric vehicles release nearly five times more global warming pollution than official figures show, as per a new analysis.

Widening Discrepancy Between Official and Actual CO2 Output

Statistics reveals that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. This contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” said a lead researcher involved in the study. “That discrepancy is growing and creates a serious issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Key Reasons Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode relative to total mileage. The team determined that just a quarter of travel was completed in electric mode, while official assumptions suggested over four-fifths.

Even, when running in electric mode, pollution levels were significantly higher than official projections. That occurred because electric motors were not strong sufficient to operate independently, leading to engines burning fossil fuels for almost one-third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled several major automaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

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

“The strong claims that manufacturers like to make about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid cars have recently been drawn again into policy debates as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large automotive industries.

Several senior officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which segments of the automotive sector claimed there was too little information to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they stated. “Any policy changes concerning PHEVs should be made with utmost care and considering that data.”