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PHEVs produce almost 5x greater global warming pollution than lab-reported data show, according to a new analysis.

Widening Gap In Official and Actual Emissions

Data reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit group. This contrasts sharply with lab tests, which assumed a 75% decrease in pollution.

Analysts studied information from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Factors Driving the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery mode compared to total mileage. The team found that just a quarter of travel was done in electric mode, whereas official estimates assumed 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab estimates. That occurred because EV motors were not strong enough to function alone, resulting to engines using fossil fuels for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions allowed four major automaker groups to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more annually in operating costs than would be estimated under laboratory conditions.

“The strong statements that manufacturers often promote about their PHEV vehicles are obviously far from the mark,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large automotive manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

An external energy economics specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which parts of the car industry argued there was too little data to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional cars,” they said. “All policy changes concerning PHEVs should be made with utmost caution and in the light of this evidence.”