Plug-in Hybrid electric Vehicles Pollute Almost as Heavily as Gasoline Cars, Study Finds

Plug-in hybrid cars produce almost 5x more global warming emissions than lab-reported figures show, as per a recent report.

Growing Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. This differs significantly with lab tests, which assumed a three-quarters reduction in pollution.

Researchers examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are decreasing,” stated a lead researcher involved in the report. “That discrepancy is growing and poses a serious problem. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to total mileage. The team determined that just a quarter of driving was done in electric mode, whereas lab assumptions assumed over four-fifths.

Additionally, when operating in electric mode, pollution amounts were well above official projections. That happened because EV motors were not strong sufficient to function independently, leading to combustion motors burning gasoline for nearly one-third of the distance covered in electric mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled four large automaker groups to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in operating expenses than would be estimated under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from member states with significant automotive industries.

Some high-level politicians have suggested plug-in hybrids as a potential “flexibility” solution to include in the regulation.

An independent energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable addition” after a long period in which segments of the car sector argued there was too little information to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” they said. “Any regulatory changes regarding PHEVs should be implemented with extreme care and considering that evidence.”