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Plug-in hybrid cars emit almost 5x greater planet-heating emissions than official figures indicate, according to a new analysis.

Widening Gap In Official and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a non-profit group. That contrasts sharply with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts studied information from onboard fuel consumption monitors of 800,000 cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a senior researcher involved in the study. “This gap is widening and poses a significant issue. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to overall distance. They found that just a quarter of travel was completed in EV mode, while official assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful sufficient to function alone, resulting to combustion motors burning fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions allowed several major automaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 extra annually in operating expenses than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Political Discussion and Automotive Pressure

Hybrid cars have lately been drawn back into policy debates as carmakers 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 EU countries with large car manufacturing.

Some high-level politicians have suggested PHEVs as a possible “compromise” option to include in the regulation.

One external energy economics expert, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the car sector argued there was insufficient data to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with extreme caution and considering this data.”