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PHEVs emit nearly five times greater planet-heating emissions than lab-reported figures indicate, according to a recent analysis.

Widening Gap In Official and Actual Emissions

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to analysis carried out by a advocacy organization. That contrasts significantly with lab estimates, which suggested a three-quarters decrease in emissions.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior analyst involved in the report. “That discrepancy is growing and poses a serious issue. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of miles driven in electric power relative to total mileage. The team found that just 27% of travel was completed in electric mode, while official estimates assumed 84%.

Even, when operating in electric mode, emission levels were significantly higher than official projections. That occurred because EV motors were not strong enough to function alone, leading to engines burning gasoline for almost one-third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several major automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 extra per year in running expenses than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the truth,” stated a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant automotive manufacturing.

Several senior officials have proposed PHEVs as a possible “compromise” option to include in the legislation.

One external energy policy specialist, who was unaffiliated with the study, called the analysis a “very useful addition” after a long period in which segments of the car industry claimed there was insufficient information to properly assess actual emissions.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel vehicles,” they said. “Any policy changes concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”