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Plug-in hybrid cars produce almost 5x more global warming pollution than official data show, according to a new report.

Widening Gap In Lab and Actual CO2 Output

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit group. This contrasts sharply with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied data from onboard energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” stated a senior analyst involved in the report. “This gap is growing and creates a significant problem. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in electric power compared to total mileage. They determined that just a quarter of travel was done in EV mode, while lab estimates assumed over four-fifths.

Additionally, when running in electric mode, emission levels were significantly higher than official estimates. That occurred because electric motors were insufficiently powerful sufficient to function alone, resulting to engines using fossil fuels for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra per year in operating costs than is estimated under laboratory tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been brought back into policy discussions as automakers have pressed the European Union to relax CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the car sector and opposition from member states with large car manufacturing.

Several senior politicians have suggested PHEVs as a potential “flexibility” option to introduce in the legislation.

One external energy policy specialist, who was not involved with the research, called the report a “highly valuable addition” after years in which segments of the car industry argued there was too little information to accurately assess actual emissions.

“These findings demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert said. “All policy changes regarding PHEVs should be implemented with extreme care and in the light of that data.”