Plug-in Hybrid Cars Pollute Almost as Much as Petrol Vehicles, Report Reveals

Plug-in hybrid electric vehicles emit almost 5x more planet-heating emissions than lab-reported data show, as per a new report.

Growing Discrepancy Between Lab and Actual Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis carried out by a advocacy organization. That differs significantly with lab tests, which assumed a 75% decrease in pollution.

Researchers studied information from onboard fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a lead researcher participating in the study. “That gap is growing and poses a significant problem. As a result, PHEVs pollute almost as much as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in battery mode compared to overall distance. The team found that just a quarter of driving was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, pollution amounts were well above lab projections. That happened because EV motors were insufficiently powerful enough to operate alone, leading to combustion motors burning fossil fuels for almost one-third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled four major carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 extra annually in operating costs than would be assumed under laboratory tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” stated a transport analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have lately been drawn again into political discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a possible “compromise” solution to include in the regulation.

An external energy economics specialist, who was not involved with the research, described the report a “highly valuable addition” after years in which segments of the automotive sector claimed there was insufficient information to accurately evaluate actual emissions.

“These findings show, without question, that the difference in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they said. “Any policy changes concerning PHEVs should be made with utmost caution and considering this data.”