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Plug-in hybrid cars release nearly five times greater global warming emissions than official figures indicate, as per a recent analysis.

Widening Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a non-profit group. This differs sharply with lab tests, which suggested a three-quarters decrease in emissions.

Analysts studied information from onboard fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” said a lead analyst participating in the report. “This gap is widening and creates a serious issue. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall distance. The team determined that only a quarter of driving was completed in electric mode, while official estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above lab projections. That occurred because EV motors were insufficiently powerful enough to function independently, leading to engines using gasoline for almost one-third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra annually in operating costs than would be estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large automotive manufacturing.

Some high-level politicians have suggested PHEVs as a potential “compromise” solution to include in the regulation.

One external energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which parts of the automotive sector claimed there was too little information to accurately assess real-world emissions.

“The results demonstrate, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel cars,” they said. “All regulatory changes concerning PHEVs should be made with utmost care and considering this data.”