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PHEVs emit almost five times more global warming pollution than official data indicate, according to a recent report.

Widening Gap Between Official and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. This contrasts significantly with laboratory tests, which assumed a 75% decrease in pollution.

Analysts studied information from onboard fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

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

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in battery mode compared to total mileage. The team determined that only a quarter of driving was completed in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were not strong enough to operate alone, leading to combustion motors using fossil fuels for almost a third of the travel covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV emissions enabled several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more annually in operating expenses than is assumed under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn again into political discussions as carmakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large automotive industries.

Several senior officials have proposed PHEVs as a potential “compromise” solution to introduce in the legislation.

An external energy policy specialist, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which segments of the automotive sector argued there was insufficient data to properly assess actual emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” they said. “All regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of this data.”