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Plug-in hybrid cars produce almost 5x more global warming pollution than official data indicate, according to a recent report.

Widening Gap In Official and Actual Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. This differs sharply with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a senior analyst participating in the study. “That gap is growing and creates a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power relative to total mileage. The team found that only 27% of travel was completed in EV mode, while official estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were well above lab estimates. This occurred because EV motors were insufficiently powerful sufficient to function alone, resulting to combustion motors using fossil fuels for almost one-third of the distance covered in EV mode.

Policy and Financial Consequences

According to 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 EU fleet-average CO₂ targets.

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

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Hybrid cars have lately been drawn back into political debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the car sector and resistance from member states with large automotive industries.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” solution to introduce in the regulation.

An independent energy policy expert, who was not involved with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the car sector claimed there was insufficient data to accurately assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they stated. “Any policy changes regarding PHEVs should be made with extreme caution and considering that evidence.”