Plug in Hybrid Vehicles Emit Almost as Much as Gasoline Cars, Study Finds
Plug-in hybrid cars produce nearly five times more global warming emissions than lab-reported figures show, according to a new analysis.
Widening Discrepancy Between Official and Actual CO2 Output
Data shows that PHEVs release only 19% lower CO2 than conventional gas and diesel cars, based on analysis carried out by a advocacy organization. That contrasts significantly with lab estimates, which assumed a 75% decrease in emissions.
Researchers studied information from in-vehicle fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO2 output from PHEVs in 2023 were nearly five times higher than official figures, up from three and a half times in 2021.
“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” said a lead analyst participating in the report. “That gap is widening and poses a serious issue. Consequently, PHEVs emit nearly as much as gasoline cars.”
Primary Factors Behind the Emissions Gap
Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power compared to total distance. They determined that only a quarter of travel was completed in electric mode, whereas official assumptions suggested over four-fifths.
Additionally, when running in electric mode, emission levels were significantly higher than official estimates. That happened because electric motors were insufficiently powerful enough to function alone, resulting to combustion motors burning gasoline for nearly one-third of the distance covered in electric mode.
Regulatory and Financial Implications
According to estimates, the underestimation of PHEV emissions allowed four major carmaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO2 targets.
Furthermore, drivers of PHEVs would spend approximately €500 extra per year in running costs than is estimated under laboratory tests.
“The bold claims that automakers like to make about their PHEV vehicles are clearly way off the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO2 emissions, and running expenses.”
Policy Debate and Automotive Pressure
Plug-in hybrid cars have recently been drawn again into political discussions as carmakers have pressed the EU to weaken CO2 targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from EU countries with large automotive manufacturing.
Some high-level officials have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.
One independent energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable contribution” after a long period in which parts of the car industry argued there was insufficient information to properly assess actual CO2 output.
“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO2 output is much, much larger than for petrol or diesel cars,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of this evidence.”
