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Plug-in hybrid electric vehicles release nearly 5x greater planet-heating emissions than lab-reported figures show, as per a recent report.

Growing Discrepancy Between Official and Actual CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a advocacy group. That contrasts sharply with lab tests, which suggested a 75% decrease in pollution.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” said a lead researcher participating in the study. “This discrepancy is growing and creates a serious issue. As a result, PHEVs pollute nearly as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery mode compared to total distance. They found that just 27% of driving was done in electric mode, whereas lab assumptions assumed 84%.

Even, when running in EV mode, pollution amounts were well above lab projections. That occurred because electric motors were not strong sufficient to operate independently, leading to engines using gasoline for nearly one-third of the travel completed in electric mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output enabled four major carmaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra annually in running costs than is assumed under laboratory conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been drawn again into political discussions as automakers have lobbied the European Union to relax CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from member states with large car industries.

Several high-level officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One external energy economics specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive sector claimed there was insufficient data to properly assess actual emissions.

“These findings demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional cars,” the expert said. “All policy changes regarding PHEVs should be made with extreme caution and in the light of this data.”