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Plug-in hybrid cars produce almost five times more planet-heating pollution than official figures show, according to a new analysis.

Widening Gap In Official and Real-World Emissions

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a non-profit organization. This differs sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “That gap is growing and poses a serious problem. As a result, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to overall mileage. They found that only a quarter of driving was completed in EV mode, while official assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution levels were well above lab estimates. That occurred because electric motors were not strong enough to operate alone, resulting to combustion motors using gasoline for almost a third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV emissions enabled four large carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 more per year in running expenses than is assumed under laboratory tests.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the truth,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

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

Some senior politicians have proposed plug-in hybrids as a possible “compromise” option to introduce in the regulation.

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

“These findings show, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert said. “All policy adjustments concerning PHEVs should be implemented with extreme caution and in the light of that data.”