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Plug-in hybrid cars release almost 5x more planet-heating pollution than lab-reported figures indicate, as per a recent analysis.

Growing Gap Between Lab and Real-World Emissions

Data reveals that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to research conducted by a non-profit organization. That differs sharply with lab tests, which assumed a 75% decrease in emissions.

Researchers studied information from onboard fuel consumption meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a lead analyst involved in the study. “This gap is widening and creates a serious issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery power compared to overall distance. The team found that just a quarter of driving was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than lab estimates. That occurred because electric motors were insufficiently powerful sufficient to operate independently, leading to engines using gasoline for almost a third of the distance completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

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

“The strong claims that automakers like to make about their plug-in hybrid cars are obviously far from the truth,” stated a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little better than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been drawn back into policy debates as automakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with significant automotive industries.

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

An external energy policy expert, who was not involved with the study, called the analysis a “very useful addition” after a long period in which segments of the car sector claimed there was insufficient data to properly evaluate actual emissions.

“The results show, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional cars,” they said. “Any policy changes concerning PHEVs should be implemented with utmost caution and in the light of this data.”