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Plug-in hybrid electric vehicles release nearly 5x more planet-heating emissions than official data show, as per a new analysis.

Widening Gap Between Official and Actual CO2 Output

Data reveals that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy group. That differs significantly with lab tests, which suggested a 75% reduction in emissions.

Researchers studied information from onboard energy use meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” stated a senior analyst involved in the study. “This gap is growing and poses a significant problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode compared to total mileage. They determined that only a quarter of travel was done in EV mode, while official assumptions suggested over four-fifths.

Even, when running in electric mode, emission amounts were significantly higher than official estimates. This happened because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors burning gasoline for nearly one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV emissions allowed several major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra per year in operating expenses than is estimated under lab tests.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the mark,” commented a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Pressure

Hybrid cars have lately been brought back into policy discussions as automakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large automotive industries.

Several senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which segments of the car sector claimed there was too little information to properly evaluate real-world emissions.

“These findings show, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or diesel vehicles,” they said. “All policy adjustments concerning PHEVs should be made with extreme care and considering that data.”