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Plug-in hybrid cars emit almost five times more global warming emissions than official data show, according to a new analysis.

Growing Gap In Official and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a non-profit group. This differs significantly with lab tests, which suggested a 75% reduction in emissions.

Analysts examined data from in-vehicle energy use monitors of eight hundred thousand 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 official figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” stated a lead analyst participating in the report. “This gap is growing and creates a serious problem. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall distance. They found that only 27% of driving was completed in EV mode, while official assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were well above lab projections. This occurred because electric motors were not strong sufficient to operate independently, resulting to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV emissions allowed several major automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 more per year in running costs than would be estimated under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn again into political debates as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with significant automotive industries.

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

An independent energy economics specialist, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which parts of the automotive sector argued there was insufficient information to accurately evaluate actual emissions.

“These findings show, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they stated. “All regulatory changes concerning PHEVs should be made with utmost care and in the light of this evidence.”