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Plug-in hybrid electric vehicles produce almost 5x greater planet-heating pollution than lab-reported figures indicate, according to a recent analysis.

Growing Discrepancy Between Lab and Actual Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on research carried out by a advocacy group. This differs sharply with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied data from onboard energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” stated a senior analyst involved in the report. “That discrepancy is growing and poses a serious issue. As a result, PHEVs pollute nearly as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in electric power compared to overall distance. The team found that just 27% of travel was done in electric mode, while lab assumptions suggested 84%.

Additionally, when running in electric mode, pollution levels were well above official projections. That happened because electric motors were insufficiently powerful enough to operate independently, resulting to combustion motors burning fossil fuels for almost one-third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed four large automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend approximately €500 extra annually in operating expenses than is assumed under laboratory conditions.

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” commented a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought again into policy debates as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from member states with large car manufacturing.

Several senior officials have proposed PHEVs as a possible “flexibility” option to introduce in the legislation.

One external energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after years in which segments of the automotive sector claimed there was too little data to properly assess real-world emissions.

“The results show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of this data.”