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PHEVs produce nearly five times greater planet-heating emissions than official figures indicate, according to a new analysis.

Widening Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, according to analysis carried out by a advocacy group. This contrasts sharply with lab tests, which assumed a 75% reduction in pollution.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a senior analyst involved in the report. “This discrepancy is growing and creates a significant issue. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery power relative to overall distance. They determined that only a quarter of travel was done in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were well above official estimates. That happened because electric motors were insufficiently powerful enough to operate alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in running costs than is estimated under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the mark,” commented a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Hybrid cars have lately been brought back into political discussions as automakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive manufacturing.

Several senior politicians have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One independent energy economics expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which parts of the car sector argued there was too little data to accurately evaluate actual emissions.

“The results show, without question, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert said. “All policy adjustments regarding PHEVs should be implemented with utmost care and in the light of this data.”