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PHEVs produce almost 5x greater global warming pollution than lab-reported figures show, according to a new report.

Widening Gap In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit group. This differs significantly with laboratory tests, which suggested a 75% decrease in pollution.

Researchers examined data from onboard fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a lead analyst participating in the study. “That discrepancy is growing and poses a serious problem. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to total distance. They found that just 27% of driving was completed in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission levels were well above official projections. This occurred because EV motors were not strong enough to operate independently, leading to combustion motors burning gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions allowed several major automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more annually in running costs than is estimated under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” stated a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from member states with large automotive manufacturing.

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

An independent energy economics expert, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the car industry argued there was insufficient data to accurately evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “Any regulatory changes regarding PHEVs should be implemented with utmost care and considering that evidence.”