Plug-in Hybrid electric Vehicles Pollute Almost as Much as Petrol Vehicles, Study Finds

Plug-in hybrid electric vehicles release almost five times more planet-heating pollution than official figures show, as per a new analysis.

Growing Discrepancy Between Official and Actual Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, according to research conducted by a advocacy group. That contrasts significantly with lab estimates, which assumed a three-quarters reduction in pollution.

Analysts studied data from onboard energy use monitors of eight hundred thousand 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 figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher involved in the report. “That gap is widening and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to total mileage. They determined that only a quarter of driving was done in electric mode, whereas lab assumptions assumed 84%.

Additionally, when running in electric mode, emission levels were well above lab estimates. This occurred because electric motors were not strong enough to function independently, resulting to combustion motors burning fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output enabled four major carmaker companies to escape over €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 more per year in running expenses than would be estimated under laboratory tests.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy discussions as automakers have lobbied the EU to relax CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with significant automotive manufacturing.

Several senior officials have suggested plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One external energy economics specialist, who was not involved with the research, called the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little data to accurately assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with extreme care and considering this evidence.”