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PHEVs release almost 5x greater planet-heating emissions than official figures indicate, as per a recent analysis.

Widening Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs emit just 19% lower CO₂ than conventional gas and diesel cars, according to research conducted by a advocacy group. This contrasts significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a senior analyst participating in the report. “This gap is growing and creates a significant problem. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in battery power relative to total distance. They found that just a quarter of driving was done in EV mode, while lab assumptions suggested 84%.

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

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled four large automaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend about €500 extra per year in running costs than would be assumed under lab conditions.

“The bold claims that manufacturers like to make about their PHEV cars are obviously way off the mark,” commented a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have lately been drawn again into political debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the car sector and resistance from EU countries with large automotive manufacturing.

Several high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

An external energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the car sector claimed there was too little data to properly assess actual emissions.

“The results show, without question, that the gap in lab and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional vehicles,” they stated. “Any policy adjustments concerning PHEVs should be made with extreme care and considering that evidence.”