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PHEVs produce almost 5x greater planet-heating emissions than official figures show, as per a new analysis.

Widening Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel vehicles, according to research conducted by a non-profit group. That contrasts sharply with laboratory estimates, which suggested a three-quarters decrease in pollution.

Analysts examined data from onboard energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a senior analyst participating in the report. “That discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode compared to total distance. The team determined that just a quarter of driving was completed in EV mode, while official assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than official projections. That occurred because EV motors were insufficiently powerful sufficient to operate alone, leading to combustion motors burning fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more per year in running expenses than would be estimated under lab tests.

“The strong claims that manufacturers like to make about their PHEV cars are obviously way off the mark,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with large car industries.

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

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

“These findings demonstrate, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they stated. “Any regulatory changes concerning PHEVs should be implemented with utmost care and considering that data.”