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Plug-in hybrid cars release almost five times more planet-heating pollution than official figures show, as per a new analysis.

Widening Discrepancy In Official and Actual Emissions

Data reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, according to research carried out by a advocacy organization. That contrasts significantly with lab tests, which suggested a 75% decrease in emissions.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” stated a lead analyst involved in the study. “That gap is widening and poses a significant problem. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to overall distance. The team determined that just a quarter of travel was done in electric mode, whereas official assumptions assumed 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab projections. That happened because electric motors were not strong enough to operate independently, leading to engines burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output enabled four major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra per year in operating expenses than would be assumed under lab tests.

“The strong statements that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with large automotive manufacturing.

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

An independent energy policy expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which parts of the automotive industry claimed there was too little data to properly assess actual CO2 output.

“These findings show, beyond any doubt, that the gap in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” the expert stated. “Any policy changes concerning PHEVs should be implemented with utmost care and considering that data.”