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

Widening Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than conventional gas and diesel cars, based on analysis carried out by a non-profit group. That contrasts significantly with lab tests, which suggested a 75% decrease in pollution.

Researchers studied information from onboard energy use monitors of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a lead analyst involved in the report. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of miles driven in electric mode compared to total mileage. They determined that only a quarter of travel was done in electric mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, pollution amounts were significantly higher than official estimates. That happened because EV motors were insufficiently powerful enough to operate independently, leading to combustion motors burning gasoline for nearly one-third of the travel completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more per year in running expenses than is assumed under lab tests.

“The bold statements that automakers often promote about their PHEV vehicles are clearly far from the mark,” commented a transport analyst. “Buyers are being duped into believing that by purchasing 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 fuel consumption, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

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

Some high-level officials have suggested plug-in hybrids as a potential “flexibility” option to introduce in the regulation.

An external energy economics expert, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the car industry argued there was insufficient information to properly assess real-world emissions.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” they said. “All regulatory adjustments regarding PHEVs should be made with extreme care and considering this evidence.”