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Plug-in hybrid cars produce almost 5x greater global warming emissions than official data indicate, as per a new report.

Growing Gap In Lab and Actual CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit organization. That differs sharply with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts examined information from onboard fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a senior analyst involved in the report. “This gap is widening and creates a significant problem. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power relative to overall distance. The team determined that just a quarter of travel was completed in electric mode, whereas lab assumptions suggested 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab projections. That occurred because electric motors were not strong enough to function independently, resulting to combustion motors burning gasoline for almost one-third of the travel completed in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled four major carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 extra annually in running expenses than is assumed under lab tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have recently been brought again into policy discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with large automotive industries.

Some senior politicians have proposed PHEVs as a potential “compromise” solution to include in the legislation.

One external energy policy expert, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which parts of the automotive industry argued there was too little data to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and considering that data.”