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PHEVs produce almost five times more global warming emissions than lab-reported figures show, according to a new report.

Widening Gap Between Lab and Actual Emissions

Data shows that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy group. This differs sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand cars sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” stated a senior analyst participating in the report. “That gap is growing and poses a serious problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Primary Factors Driving the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total distance. They found that just 27% of driving was done in electric mode, whereas official assumptions assumed 84%.

Additionally, when running in electric mode, emission amounts were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV emissions allowed four major automaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra annually in operating expenses than is assumed under laboratory conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large car industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

An external energy policy expert, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the car sector argued there was insufficient data 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 significantly larger than for gasoline or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be implemented with extreme caution and in the light of that data.”