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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than official data indicate, according to a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Statistics shows that PHEVs release just one-fifth less CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit organization. That contrasts sharply with laboratory estimates, which assumed a 75% decrease in emissions.

Researchers studied data from in-vehicle energy use monitors of 800,000 cars sold in the EU from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a lead analyst participating in the report. “That discrepancy is widening and creates a serious issue. Consequently, PHEVs emit almost as much as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric power relative to total mileage. The team found that just a quarter of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful sufficient to function alone, resulting to engines using gasoline for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four major carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating costs than would be assumed under lab tests.

“The bold claims that automakers often promote about their PHEV cars are clearly far from the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn again into political discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with large car industries.

Some high-level politicians have proposed plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An external energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was too little data to accurately assess real-world emissions.

“These findings demonstrate, without question, that the difference in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” the expert said. “All regulatory changes regarding PHEVs should be made with extreme caution and in the light of that data.”