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Plug-in hybrid cars produce nearly five times more global warming pollution than lab-reported data indicate, according to a new report.

Widening Gap Between Official and Actual Emissions

Data reveals that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a advocacy group. That differs sharply with lab tests, which suggested a 75% decrease in pollution.

Analysts studied information from onboard fuel consumption monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” stated a lead researcher involved in the report. “That discrepancy is growing and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery mode compared to overall mileage. They determined that just a quarter of travel was completed in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, pollution levels were well above lab projections. That happened because EV motors were insufficiently powerful enough to function alone, leading to combustion motors using fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled four large automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

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

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

Political Discussion and Industry Pressure

Hybrid vehicles have lately been brought again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with large car industries.

Some high-level politicians have proposed PHEVs as a possible “compromise” solution to include in the regulation.

An external energy policy specialist, who was not involved with the study, described the report a “very useful contribution” after a long period in which parts of the automotive industry claimed there was too little information to accurately assess actual CO2 output.

“These findings show, without question, that the gap between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that data.”