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PHEVs release nearly 5x more planet-heating pollution than lab-reported data indicate, as per a recent report.

Growing Gap Between Lab and Actual Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit group. That contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Researchers studied data from onboard fuel consumption monitors of 800,000 cars sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” stated a lead analyst involved in the report. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery mode relative to overall mileage. The team determined that only a quarter of driving was done in electric mode, while lab assumptions assumed 84%.

Even, when operating in EV mode, pollution levels were well above lab estimates. That happened because EV motors were not strong enough to function independently, resulting to combustion motors using gasoline for nearly a third of the travel completed in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled four large carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in operating expenses than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their PHEV cars are clearly far from the mark,” commented a transport expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Pressure

Hybrid vehicles have lately been brought again into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from member states with large car manufacturing.

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

An independent energy policy expert, who was unaffiliated with the study, called the report a “very useful contribution” after years in which parts of the car sector claimed there was insufficient information to accurately evaluate real-world emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert said. “All policy adjustments regarding PHEVs should be made with utmost caution and in the light of that evidence.”