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Plug-in hybrid cars produce nearly five times more global warming emissions than official figures show, according to a recent analysis.

Growing Gap In Lab and Actual Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This differs sharply with lab tests, which assumed a 75% decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher participating in the study. “This discrepancy is growing and creates a serious issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles travelled in battery power relative to overall mileage. They found that just 27% of driving was done in electric mode, while official estimates assumed 84%.

Even, when operating in EV mode, emission amounts were significantly higher than lab projections. This occurred because EV motors were not strong enough to function alone, leading to combustion motors burning fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output enabled several major carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would pay about €500 extra annually in operating costs than is estimated under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have lately been drawn again into political discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from member states with significant car industries.

Several senior officials have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

An independent energy policy expert, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little information to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert said. “Any policy adjustments concerning PHEVs should be made with extreme care and in the light of that data.”