🔗 Share this article

Plug-in hybrid electric vehicles release almost 5x greater global warming pollution than lab-reported figures show, according to a new analysis.

Growing Discrepancy Between Lab and Actual CO2 Output

Data shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit group. This differs sharply with lab estimates, which suggested a three-quarters decrease in emissions.

Analysts examined information from onboard fuel consumption monitors of 800,000 cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a lead researcher involved in the study. “That gap is growing and poses a significant issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power relative to total mileage. They found that just 27% of travel was completed in EV mode, whereas official estimates assumed 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than official projections. That occurred because electric motors were not strong enough to operate alone, leading to engines using gasoline for almost one-third of the travel completed in electric mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled several large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay about €500 extra per year in operating costs than would be assumed under lab tests.

“The strong claims that automakers often promote about their plug-in hybrid cars are obviously far from the truth,” stated a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn again into policy discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which segments of the automotive sector argued there was too little information to properly assess actual CO2 output.

“These findings demonstrate, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or conventional cars,” they stated. “All regulatory changes regarding PHEVs should be made with utmost care and considering that data.”