Plug-in Hybrid electric Cars Pollute Almost as Much as Petrol Cars, Report Finds

Plug-in hybrid electric vehicles release almost 5x more planet-heating emissions than lab-reported figures indicate, according to a new analysis.

Widening Gap Between Lab and Actual Emissions

Data shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, based on analysis conducted by a advocacy organization. That contrasts sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Researchers examined information from onboard fuel consumption monitors of 800,000 vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” said a senior analyst participating in the study. “This discrepancy is widening and creates a serious problem. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to overall mileage. They found that just a quarter of travel was done in EV mode, while official estimates assumed 84%.

Even, when operating in EV mode, pollution amounts were well above official estimates. That happened because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning gasoline for nearly a third of the distance covered in electric mode.

Regulatory and Economic Implications

According to calculations, the underestimation of PHEV emissions enabled several major automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend about €500 extra per year in operating costs than is assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly way off the mark,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into political debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and resistance from member states with large automotive industries.

Several senior politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An external energy economics specialist, who was unaffiliated with the study, described the report a “very useful contribution” after years in which parts of the automotive sector claimed there was too little information to properly assess actual CO2 output.

“These findings show, without question, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they said. “All regulatory adjustments concerning PHEVs should be made with utmost caution and in the light of this evidence.”