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Plug-in hybrid cars release almost 5x more global warming emissions than lab-reported figures show, as per a new analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than traditional gas and diesel cars, according to research conducted by a non-profit group. This differs significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts examined information from onboard fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” stated a senior researcher involved in the report. “This gap is growing and creates a serious issue. As a result, PHEVs pollute almost as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power relative to total distance. The team found that just a quarter of driving was completed in EV mode, while official estimates suggested 84%.

Additionally, when operating in EV mode, emission amounts were well above official estimates. This happened because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors using fossil fuels for almost a third of the distance completed in electric mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed several large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in operating expenses than would be estimated under lab conditions.

“The strong claims that manufacturers like to make about their PHEV cars are clearly way off the mark,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been brought back into policy debates as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from member states with large car industries.

Some high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the car industry argued there was insufficient data to accurately evaluate real-world CO2 output.

“These findings demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” they said. “Any regulatory changes concerning PHEVs should be made with extreme caution and in the light of that data.”