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PHEVs release nearly 5x more global warming emissions than lab-reported data indicate, according to a recent report.

Widening Gap Between Official and Real-World Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel cars, according to research conducted by a advocacy organization. This differs sharply with laboratory tests, which suggested a 75% reduction in emissions.

Researchers examined data from onboard energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a lead researcher participating in the report. “This gap is widening and poses a serious issue. As a result, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total mileage. They found that only 27% of travel was done in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above lab estimates. This happened because EV motors were insufficiently powerful sufficient to operate alone, resulting to engines using fossil fuels for nearly a third of the distance completed in electric mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four major automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in running expenses than is assumed under lab conditions.

“The bold statements that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Hybrid cars have lately been drawn again into political debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car manufacturing.

Several senior politicians have proposed PHEVs as a possible “flexibility” option to introduce in the regulation.

One independent energy policy expert, who was not involved with the study, called the analysis a “very useful contribution” after a long period in which parts of the car industry argued there was insufficient information to accurately assess actual emissions.

“These findings show, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering that evidence.”