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PHEVs emit nearly 5x more global warming emissions than official figures indicate, according to a new analysis.

Widening Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than traditional petrol and diesel cars, according to analysis conducted by a advocacy organization. This differs sharply with lab estimates, which suggested a 75% decrease in emissions.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are falling,” stated a senior researcher participating in the report. “This gap is widening and poses a serious issue. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to total mileage. The team found that just a quarter of driving was completed in electric mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in electric mode, emission levels were significantly higher than official estimates. This happened because EV motors were not strong sufficient to function independently, resulting to combustion motors using gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions enabled several large automaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more annually in running costs than would be estimated under lab conditions.

“The strong claims that automakers often promote about their PHEV vehicles are clearly far from the truth,” stated a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as carmakers have lobbied the EU to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with large automotive manufacturing.

Several senior politicians have proposed plug-in hybrids as a possible “compromise” solution to include in the legislation.

One independent energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable addition” after years in which segments of the automotive industry claimed there was insufficient data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “Any policy changes concerning PHEVs should be made with extreme caution and in the light of that evidence.”