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Plug-in hybrid cars release almost five times more global warming emissions than lab-reported figures indicate, as per a new report.

Growing Gap Between Lab and Actual CO2 Output

Statistics reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit group. This contrasts significantly with lab estimates, which assumed a 75% reduction in emissions.

Researchers studied information from onboard fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” stated a lead analyst involved in the study. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode compared to overall distance. The team determined that just 27% of driving was completed in electric mode, while official estimates assumed 84%.

Additionally, when operating in electric mode, pollution amounts were well above lab projections. This happened because EV motors were not strong sufficient to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four major carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 more annually in operating costs than is assumed under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” commented 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 better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as automakers have lobbied the EU to relax CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from member states with significant automotive industries.

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

One external energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable addition” after years in which segments of the car sector argued there was too little data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be made with utmost care and considering this data.”