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Plug-in hybrid electric vehicles release nearly 5x greater global warming emissions than lab-reported figures indicate, according to a recent analysis.

Widening Gap Between Lab and Actual CO2 Output

Data shows that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy group. This differs sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher involved in the study. “That gap is widening and creates a significant problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric mode compared to total distance. They determined that only 27% of driving was completed in EV mode, while official assumptions suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above lab projections. This occurred because EV motors were not strong enough to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV emissions allowed four major automaker companies to escape over €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 more annually in operating costs than would be assumed under laboratory conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn again into political discussions as automakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant car manufacturing.

Some high-level officials have proposed PHEVs as a possible “flexibility” option to introduce in the legislation.

An independent energy policy specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which segments of the car sector claimed there was too little data to accurately assess actual emissions.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional cars,” the expert said. “Any policy changes concerning PHEVs should be implemented with extreme care and considering that evidence.”