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PHEVs release almost 5x greater global warming pollution than official data show, as per a new analysis.

Growing Gap Between Official and Actual CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy group. This contrasts significantly with laboratory tests, which assumed a 75% reduction in pollution.

Analysts studied information from onboard energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” stated a senior analyst participating in the study. “This gap is widening and creates a serious issue. As a result, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode relative to overall mileage. The team found that only a quarter of travel was done in electric mode, whereas official assumptions assumed 84%.

Even, when running in electric mode, emission levels were significantly higher than official estimates. That happened because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors burning gasoline for almost one-third of the travel covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed four large automaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in operating expenses than is estimated under lab conditions.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid vehicles have recently been brought again into political discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with significant automotive manufacturing.

Some high-level politicians have suggested plug-in hybrids as a possible “compromise” option to include in the regulation.

An independent energy policy expert, who was not involved with the study, called the report a “highly valuable contribution” after years in which segments of the automotive sector claimed there was insufficient data to accurately assess real-world emissions.

“The results show, without question, that the gap in official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and considering this data.”