🔗 Share this article

Plug-in hybrid electric vehicles release almost 5x more global warming pollution than lab-reported data indicate, according to a recent analysis.

Widening Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a non-profit organization. That differs sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from onboard energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are falling,” said a lead analyst participating in the report. “This gap is widening and poses a significant issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery mode compared to overall mileage. The team determined that only a quarter of travel was done in EV mode, whereas official estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission levels were well above official estimates. That happened because EV motors were not strong enough to function alone, leading to combustion motors using gasoline for almost one-third of the distance completed in EV mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV emissions allowed four large automaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in running costs than is estimated under lab tests.

“The strong claims that automakers often promote about their PHEV vehicles are obviously far from the truth,” stated a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political discussions as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with large automotive industries.

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

An external energy policy expert, who was unaffiliated with the study, described the report a “very useful contribution” after a long period in which parts of the car sector argued there was too little data to properly assess actual emissions.

“These findings demonstrate, without question, that the gap between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional vehicles,” they said. “Any policy changes concerning PHEVs should be implemented with utmost caution and in the light of that data.”