🔗 Share this article

Plug-in hybrid electric vehicles release nearly five times more global warming pollution than official figures indicate, according to a recent analysis.

Widening Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit organization. That differs significantly with lab estimates, which assumed a 75% reduction in emissions.

Analysts studied information from onboard fuel consumption meters of eight hundred thousand cars registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” said a senior analyst involved in the report. “This gap is growing and poses a significant problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in electric mode compared to total distance. The team determined that only 27% of driving was completed in EV mode, while official assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were well above official projections. This occurred because electric motors were not strong sufficient to function alone, resulting to combustion motors using gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra per year in operating costs than is assumed under laboratory conditions.

“The strong statements that automakers like to make about their PHEV vehicles are obviously way off the truth,” stated a transport analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into policy debates as automakers have pressed the European Union to relax CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large automotive industries.

Some senior politicians have proposed PHEVs as a potential “flexibility” option to include in the legislation.

An external energy policy specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after a long period in which parts of the car sector argued there was insufficient information to properly assess real-world CO2 output.

“The results show, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost caution and in the light of that data.”