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PHEVs emit almost 5x more planet-heating pollution than official data indicate, as per a recent report.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This differs significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers studied information from onboard energy use monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” said a lead researcher participating in the report. “That gap is widening and creates a significant issue. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts linked most of the difference to overestimates of the “utility factor” – the percentage of miles driven in battery power relative to overall mileage. They determined that just a quarter of driving was completed in EV mode, while official assumptions suggested 84%.

Even, when running in EV mode, pollution levels were significantly higher than official projections. This happened because electric motors were not strong sufficient to function alone, resulting to engines using fossil fuels for almost one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 more per year in operating costs than would be estimated under lab conditions.

“The strong statements that manufacturers like to make about their PHEV cars are obviously way off the mark,” stated a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than standard petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with significant car manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “flexibility” option to include in the legislation.

An external energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after years in which parts of the automotive sector argued there was insufficient data to accurately assess real-world CO2 output.

“The results show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional cars,” they stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and in the light of this data.”