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Plug-in hybrid electric vehicles emit almost 5x more global warming emissions than official figures show, as per a new report.

Growing Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a non-profit group. That differs sharply with lab tests, which suggested a 75% reduction in pollution.

Analysts studied data from onboard energy use monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a lead analyst involved in the study. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery power relative to overall mileage. The team found that only 27% of travel was completed in electric mode, while lab assumptions assumed 84%.

Even, when operating in EV mode, pollution levels were significantly higher than lab estimates. This happened because EV motors were not strong enough to function independently, resulting to combustion motors burning gasoline for almost a third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could pay approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The strong statements that automakers often promote about their plug-in hybrid cars are obviously way off the mark,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been brought back into political debates as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large car manufacturing.

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

One external energy economics expert, who was unaffiliated with the study, described the report a “very useful contribution” after a long period in which segments of the car sector argued there was too little information to accurately evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert said. “Any policy changes concerning PHEVs should be made with utmost caution and considering that data.”