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Plug-in hybrid electric vehicles emit almost five times more global warming emissions than lab-reported figures show, as per a new analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy group. That differs sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a lead analyst participating in the report. “This gap is widening and poses a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode compared to overall mileage. They determined that just a quarter of travel was completed in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in EV mode, emission levels were well above official estimates. This happened because electric motors were not strong enough to operate independently, leading to combustion motors using fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Financial Implications

According to calculations, the underestimation of PHEV CO2 output enabled four large automaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could pay about €500 more per year in operating expenses than is estimated under laboratory tests.

“The strong claims that manufacturers like to make about their PHEV cars are obviously far from the mark,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large car manufacturing.

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

An independent energy policy expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which segments of the automotive sector argued there was too little information to accurately evaluate real-world emissions.

“These findings show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” they stated. “All policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that evidence.”