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Plug-in hybrid cars emit almost five times more global warming emissions than official figures show, as per a new report.

Growing Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. This differs significantly with lab estimates, which suggested a three-quarters decrease in emissions.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a lead analyst participating in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode compared to total mileage. They determined that only a quarter of driving was done in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official estimates. This happened because electric motors were not strong enough to operate alone, resulting to combustion motors using gasoline for nearly a third of the travel covered in EV mode.

Policy and Economic Consequences

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

Furthermore, drivers of PHEVs could spend approximately €500 more annually in running expenses than is assumed under laboratory tests.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been brought again into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large car industries.

Some senior officials have suggested plug-in hybrids as a possible “flexibility” option to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, called the report a “very useful contribution” after years in which segments of the automotive sector claimed there was insufficient information to accurately evaluate real-world emissions.

“The results demonstrate, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” the expert said. “All regulatory changes regarding PHEVs should be made with utmost caution and considering that evidence.”