Plug-in Hybrid Cars Emit Almost as Heavily as Petrol Vehicles, Study Finds

Plug-in hybrid electric vehicles produce almost five times more global warming emissions than official figures indicate, according to a new report.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit organization. This differs significantly with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior analyst involved in the report. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode compared to total distance. The team determined that only 27% of driving was completed in electric mode, while lab estimates suggested over four-fifths.

Additionally, when running in EV mode, pollution levels were well above lab projections. This happened because electric motors were not strong sufficient to function alone, resulting to engines using fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed several large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs would spend about €500 extra annually in running costs than would be assumed under lab conditions.

“The bold claims that manufacturers like to make about their PHEV cars are obviously far from the mark,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into policy debates as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant car manufacturing.

Several high-level officials have suggested plug-in hybrids as a potential “compromise” solution to include in the regulation.

An external energy economics expert, who was unaffiliated with the study, described the report a “highly valuable addition” after a long period in which segments of the car industry argued there was too little information to accurately evaluate real-world emissions.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” the expert said. “All policy changes regarding PHEVs should be made with extreme care and considering this evidence.”