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PHEVs release almost 5x greater planet-heating emissions than lab-reported figures indicate, according to a recent report.

Growing Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy organization. That contrasts significantly with laboratory tests, which assumed a three-quarters reduction in pollution.

Researchers examined information from onboard fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a lead analyst participating in the report. “This discrepancy is widening and creates a serious problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode relative to total distance. They determined that only 27% of travel was completed in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above official projections. This happened because EV motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

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

Additionally, drivers of PHEVs could pay approximately €500 extra annually in running costs than is estimated under lab tests.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the mark,” commented a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Industry Lobbying

Hybrid vehicles have lately been brought again into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with large automotive industries.

Some high-level officials have proposed PHEVs as a potential “flexibility” option to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which segments of the automotive industry argued there was too little information to accurately evaluate real-world CO2 output.

“These findings show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or diesel vehicles,” they stated. “All policy changes regarding PHEVs should be made with utmost care and in the light of this data.”