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Plug-in hybrid electric vehicles produce almost five times greater planet-heating pollution than lab-reported data indicate, as per a new analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit group. That differs significantly with lab estimates, which suggested a 75% decrease in emissions.

Researchers examined information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” stated a lead analyst participating in the report. “This gap is widening and poses a significant problem. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery power compared to overall mileage. They determined that only 27% of travel was completed in electric mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above official projections. This occurred because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors burning gasoline for nearly a third of the travel covered in electric mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled several large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 more per year in running costs than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been drawn again into political debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with large car manufacturing.

Several high-level politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

One independent energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which segments of the car sector claimed there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional vehicles,” the expert said. “Any policy adjustments concerning PHEVs should be implemented with utmost caution and considering that evidence.”