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Plug-in hybrid electric vehicles produce almost five times more planet-heating pollution than lab-reported figures show, as per a recent analysis.

Growing Discrepancy Between Official and Actual Emissions

Data shows that PHEVs release only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a non-profit group. This contrasts sharply with lab estimates, which suggested a 75% decrease in emissions.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a lead analyst involved in the study. “That gap is growing and creates a significant problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Primary Factors Behind the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power relative to total mileage. The team found that just a quarter of driving was done in EV mode, while official estimates assumed 84%.

Even, when operating in electric mode, pollution levels were well above official projections. This occurred because EV motors were not strong enough to operate independently, leading to engines using gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed four major automaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 extra per year in running costs than would be estimated under laboratory conditions.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the mark,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought back into policy discussions as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with significant car industries.

Some senior politicians have suggested plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

An external energy policy expert, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the automotive sector argued there was too little information to properly assess actual CO2 output.

“These findings show, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be made with extreme care and considering that evidence.”