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PHEVs release nearly 5x more planet-heating pollution than lab-reported data indicate, according to a new report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy organization. That contrasts significantly with lab tests, which suggested a 75% decrease in pollution.

Researchers examined data from in-vehicle fuel consumption meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead analyst participating in the study. “This gap is growing and poses a serious issue. As a result, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total distance. They determined that only a quarter of driving was done in electric mode, while official assumptions suggested over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using gasoline for almost one-third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed several major carmaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

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

“The strong statements that automakers often promote about their PHEV cars are clearly way off the mark,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been drawn back into policy debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the car sector and resistance from EU countries with significant automotive industries.

Several senior politicians have suggested plug-in hybrids as a potential “flexibility” option to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the study, described the report a “very useful addition” after years in which parts of the automotive sector claimed there was insufficient information to properly assess actual CO2 output.

“The results show, without question, that the difference in official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” the expert said. “All regulatory adjustments regarding PHEVs should be made with utmost care and in the light of that data.”