Plug-in Hybrid electric Vehicles Pollute Nearly as Much as Gasoline Vehicles, Study Finds

Plug-in hybrid cars emit nearly 5x more global warming pollution than official data show, as per a new analysis.

Widening Gap Between Official and Actual CO2 Output

Statistics reveals that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to research conducted by a non-profit group. That contrasts sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a senior analyst participating in the report. “This gap is widening and poses a serious issue. As a result, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total distance. The team determined that just 27% of travel was done in electric mode, whereas official estimates assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to function alone, leading to engines using gasoline for nearly a third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions enabled four large automaker companies to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 extra per year in running expenses than is estimated under lab conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Hybrid cars have lately been brought again into policy discussions as automakers 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 sector and resistance from member states with large automotive industries.

Several high-level officials have proposed PHEVs as a possible “compromise” option to introduce in the legislation.

One external energy economics specialist, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the automotive sector claimed there was insufficient information to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel cars,” they said. “Any policy adjustments regarding PHEVs should be made with utmost care and considering this evidence.”