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PHEVs release nearly 5x more global warming pollution than lab-reported data show, as per a recent report.

Widening Gap Between Lab and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a advocacy group. That differs sharply with lab tests, which suggested a 75% decrease in emissions.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand cars registered in Europe from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a lead analyst participating in the study. “This gap is growing and poses a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery mode compared to overall distance. They determined that only a quarter of travel was done in EV mode, whereas lab assumptions suggested 84%.

Additionally, when running in EV mode, emission amounts were significantly higher than lab estimates. This happened because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors using gasoline for almost one-third of the distance completed in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in operating expenses than would be estimated under lab conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into policy debates as automakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with significant car industries.

Several high-level politicians have suggested PHEVs as a possible “compromise” option to include in the regulation.

An external energy policy specialist, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after years in which segments of the automotive industry claimed there was insufficient data to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” they said. “All regulatory adjustments concerning PHEVs should be made with utmost care and considering that data.”