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Plug-in hybrid cars emit nearly 5x more planet-heating emissions than official data show, according to a new analysis.

Widening Discrepancy Between Official and Actual CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a advocacy group. That contrasts sharply with lab tests, which assumed a 75% reduction in emissions.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” stated a lead analyst participating in the study. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to overall mileage. The team found that only 27% of driving was done in electric mode, whereas official estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission levels were significantly higher than official estimates. That occurred because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors using gasoline for nearly a third of the travel completed in electric mode.

Policy and Financial Consequences

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

Furthermore, owners of PHEVs could spend about €500 extra annually in operating expenses than is assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously way off the truth,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. Actually, PHEVs are little improved than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have recently been brought again into policy discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with large car industries.

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

One external energy policy expert, who was not involved with the study, called the analysis a “very useful contribution” after years in which parts of the automotive industry claimed there was insufficient data to properly assess real-world emissions.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they said. “All regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering this data.”