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PHEVs emit nearly five times more global warming emissions than lab-reported figures show, according to a new analysis.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit group. This differs sharply with laboratory tests, which suggested a three-quarters decrease in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 cars sold in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior researcher participating in the study. “That gap is widening and poses a significant issue. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Factors Driving the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in electric power relative to total distance. They determined that just 27% of travel was completed in electric mode, while official assumptions suggested over four-fifths.

Additionally, when operating in electric mode, pollution amounts were well above official estimates. That happened because electric motors were insufficiently powerful sufficient to function independently, leading to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four major automaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 extra annually in running expenses than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid cars have recently been drawn again into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with significant automotive manufacturing.

Several high-level politicians have suggested PHEVs as a possible “flexibility” solution to include in the regulation.

One external energy policy specialist, who was unaffiliated with the research, described the analysis a “very useful addition” after years in which parts of the automotive industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert said. “All regulatory changes concerning PHEVs should be made with utmost caution and in the light of this evidence.”