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Plug-in hybrid cars emit almost 5x more global warming emissions than lab-reported figures indicate, according to a recent analysis.

Growing Gap Between Official and Real-World Emissions

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel vehicles, based on research conducted by a non-profit organization. That contrasts significantly with lab tests, which suggested a three-quarters reduction in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of 800,000 cars sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst participating in the study. “This gap is growing and creates a significant problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery power compared to total distance. They determined that just 27% of travel was done in electric mode, whereas lab estimates assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above official estimates. That happened because EV motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning fossil fuels for nearly a third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more per year in operating expenses than is estimated under lab tests.

“The strong claims that manufacturers often promote about their PHEV cars are obviously way off the mark,” commented a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into political debates as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with significant car manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An independent energy economics specialist, who was not involved with the research, called the report a “highly valuable addition” after years in which parts of the car sector claimed there was insufficient data to accurately evaluate actual CO2 output.

“These findings show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” they stated. “Any regulatory changes concerning PHEVs should be made with utmost caution and considering this data.”