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Plug-in hybrid cars produce almost five times more global warming pollution than lab-reported figures show, as per a recent analysis.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on research carried out by a advocacy organization. This differs significantly with laboratory tests, which suggested a three-quarters decrease in emissions.

Researchers studied data from onboard fuel consumption monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a senior analyst involved in the report. “This gap is growing and creates a serious issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to overall distance. The team found that only 27% of travel was done in electric mode, while lab assumptions assumed over four-fifths.

Even, when running in EV mode, emission amounts were significantly higher than official estimates. That happened because electric motors were not strong sufficient to function alone, leading to engines burning fossil fuels for nearly a third of the travel covered in electric mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more annually in operating expenses than would be estimated under laboratory conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have lately been brought again into political debates as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive manufacturing.

Some senior officials have suggested PHEVs as a potential “flexibility” option to include in the legislation.

One independent energy economics expert, who was unaffiliated with the research, called the report a “highly valuable contribution” after years in which segments of the car sector argued there was too little data to properly evaluate actual emissions.

“The results show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with extreme care and in the light of that data.”