🔗 Share this article

PHEVs release almost 5x more global warming pollution than lab-reported figures indicate, according to a new analysis.

Growing Gap Between Official and Real-World CO2 Output

Statistics reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis carried out by a non-profit organization. That differs significantly with laboratory tests, which assumed a 75% decrease in emissions.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand vehicles sold 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 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” stated a senior researcher involved in the report. “That discrepancy is widening and poses a significant issue. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode compared to overall distance. The team determined that just 27% of driving was completed in electric mode, while lab estimates suggested 84%.

Even, when operating in EV mode, pollution amounts were well above official estimates. This happened because electric motors were not strong sufficient to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Economic Consequences

According to estimates, the underestimation of PHEV emissions enabled four large carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 more per year in operating costs than is assumed under lab conditions.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the truth,” stated a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from member states with large car manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One external energy policy specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which parts of the automotive sector argued there was too little information to accurately evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” they said. “Any regulatory changes concerning PHEVs should be implemented with extreme caution and considering that evidence.”