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PHEVs produce almost five times more global warming pollution than official data indicate, according to a recent analysis.

Growing Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy group. That contrasts significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” stated a senior analyst participating in the report. “This gap is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode compared to overall distance. They found that just a quarter of driving was completed in EV mode, whereas official assumptions suggested 84%.

Additionally, when operating in EV mode, emission levels were well above lab projections. That occurred because EV motors were not strong enough to operate alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed several large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 more annually in operating costs than would be estimated under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are obviously way off the truth,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into policy discussions as carmakers have pressed the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large car industries.

Some senior politicians have proposed PHEVs as a possible “compromise” option to include in the legislation.

An independent energy policy expert, who was not involved with the research, called the report a “very useful addition” after a long period in which segments of the car sector argued there was insufficient data to properly assess actual CO2 output.

“These findings demonstrate, without question, that the difference between lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and considering that evidence.”