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Plug-in hybrid electric vehicles produce nearly five times more global warming pollution than lab-reported data show, according to a recent analysis.

Widening Gap In Official and Actual CO2 Output

Statistics shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy group. That differs significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a lead analyst involved in the study. “That gap is growing and poses a significant issue. Consequently, PHEVs emit nearly as much as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power compared to total distance. The team determined that just a quarter of driving was completed in electric mode, while lab estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above lab estimates. That occurred because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors burning gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled several large carmaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more annually in operating expenses than would be estimated under lab tests.

“The bold statements that manufacturers often promote about their PHEV cars are obviously far from the truth,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with significant car manufacturing.

Some senior politicians have proposed plug-in hybrids as a potential “flexibility” option to include in the regulation.

An external energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after a long period in which segments of the car industry claimed there was insufficient information to properly evaluate actual CO2 output.

“These findings show, without question, that the difference between official and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or conventional vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with utmost care and considering this data.”