Plug in Hybrid Cars Emit Almost as Much as Gasoline Vehicles, Study Finds

Plug-in hybrid electric vehicles produce almost 5x greater planet-heating pollution than official figures indicate, according to a recent report.

Growing Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a advocacy organization. That differs significantly with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a senior analyst participating in the report. “This discrepancy is widening and poses a significant issue. As a result, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to total distance. The team determined that just a quarter of driving was completed in EV mode, while official estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above official projections. This happened because EV motors were not strong sufficient to function alone, leading to combustion motors burning gasoline for nearly a third of the travel covered in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV CO2 output enabled four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more annually in operating costs than would be assumed under lab tests.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large car manufacturing.

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

One external energy economics specialist, who was unaffiliated with the study, described the report a “very useful contribution” after years in which segments of the car industry argued there was insufficient information to properly evaluate actual CO2 output.

“The results show, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert said. “All regulatory changes regarding PHEVs should be made with utmost care and in the light of that evidence.”