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Plug-in hybrid cars produce almost 5x greater global warming emissions than lab-reported data indicate, according to a recent analysis.

Widening Gap In Lab and Real-World Emissions

Statistics reveals that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy organization. This differs sharply with lab estimates, which suggested a 75% decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a lead analyst participating in the study. “That discrepancy is widening and poses a serious issue. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power relative to total distance. The team found that only 27% of travel was completed in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution amounts were significantly higher than official estimates. This occurred because electric motors were not strong sufficient to operate alone, resulting to combustion motors burning gasoline for nearly a third of the travel completed in electric mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV CO2 output enabled several major automaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra annually in running costs than would be estimated under lab tests.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are obviously way off the truth,” commented a transport analyst. “Consumers are being duped into thinking 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 running expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and resistance from member states with significant car manufacturing.

Several senior officials have suggested plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An external energy economics expert, who was not involved with the study, called the analysis a “very useful contribution” after years in which segments of the automotive sector argued there was too little information to properly assess actual CO2 output.

“The results show, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert said. “All policy changes concerning PHEVs should be made with extreme caution and considering that evidence.”