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Plug-in hybrid cars produce almost five times more global warming emissions than lab-reported figures show, according to a new analysis.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel vehicles, according to research carried out by a advocacy organization. This differs sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered 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 estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a lead researcher involved in the report. “That gap is growing and creates a serious problem. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric mode relative to total mileage. They determined that just a quarter of travel was completed in electric mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in electric mode, emission levels were well above lab estimates. That happened because electric motors were not strong sufficient to operate independently, resulting to combustion motors using gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV emissions enabled several large automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra annually in running expenses than would be estimated under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been brought back into political debates as carmakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with significant automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” option to include in the regulation.

An independent energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the car industry argued there was insufficient information to accurately evaluate actual CO2 output.

“The results demonstrate, without question, that the gap in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they stated. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and considering that data.”