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Plug-in hybrid electric vehicles produce almost five times more global warming pollution than lab-reported figures show, as per a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy organization. This differs sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers examined information from in-vehicle energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are falling,” said a senior researcher involved in the report. “That gap is widening and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric power compared to total mileage. They determined that only a quarter of driving was completed in EV mode, while lab estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than official projections. That occurred because EV motors were insufficiently powerful enough to function alone, resulting to combustion motors using fossil fuels for nearly a third of the travel covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 extra per year in running expenses than is estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” commented a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large automotive manufacturing.

Some high-level politicians have proposed plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One independent energy economics specialist, who was not involved with the study, called the report a “very useful contribution” after a long period in which parts of the automotive sector claimed there was too little information to properly assess actual CO2 output.

“The results show, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert said. “Any policy adjustments regarding PHEVs should be implemented with utmost caution and considering that data.”