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PHEVs produce almost 5x more planet-heating pollution than lab-reported data show, as per a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy group. This differs significantly with laboratory estimates, which assumed a 75% decrease in emissions.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” said a senior analyst participating in the report. “That gap is widening and creates a serious problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in electric power relative to overall distance. They determined that only 27% of travel was completed in EV mode, while official assumptions assumed 84%.

Additionally, when operating in EV mode, pollution amounts were well above official projections. That occurred because EV motors were insufficiently powerful sufficient to function alone, leading to combustion motors using gasoline for almost a third of the travel covered in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in running expenses than is assumed under laboratory tests.

“The strong claims that automakers often promote about their PHEV vehicles are obviously far from the truth,” commented a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from member states with large automotive manufacturing.

Several senior officials have suggested PHEVs as a potential “compromise” option to include in the legislation.

An external energy policy expert, who was unaffiliated with the study, called the analysis a “very useful addition” after years in which parts of the car industry argued there was too little data to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” they said. “All policy changes concerning PHEVs should be made with extreme care and considering that data.”