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PHEVs release nearly five times greater planet-heating emissions than official data show, according to a new analysis.

Growing Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy group. This differs sharply with lab tests, which suggested a three-quarters decrease in pollution.

Analysts studied information from onboard fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and poses a significant issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to overall distance. They determined that just 27% of driving was done in electric mode, whereas lab estimates suggested 84%.

Additionally, when operating in electric mode, pollution levels were well above lab projections. That occurred because electric motors were not strong sufficient to operate independently, leading to combustion motors using gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled several large automaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 extra per year in running expenses than is estimated under lab tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are clearly way off the truth,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have recently been brought again into political debates as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with large automotive manufacturing.

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

An external energy policy expert, who was unaffiliated with the study, described the report a “highly valuable addition” after years in which segments of the automotive industry argued there was too little data to properly evaluate real-world emissions.

“These findings demonstrate, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel cars,” they stated. “All policy adjustments concerning PHEVs should be made with utmost care and considering this evidence.”