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Plug-in hybrid cars produce almost 5x more global warming pollution than lab-reported data show, as per a new report.

Growing Gap In Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, according to research carried out by a non-profit group. This contrasts significantly with laboratory tests, which assumed a 75% decrease in pollution.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” said a senior analyst involved in the report. “That gap is widening and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to total mileage. They found that just 27% of driving was done in electric mode, while lab estimates assumed 84%.

Additionally, when running in EV mode, pollution levels were significantly higher than lab estimates. This happened because EV motors were insufficiently powerful enough to function alone, leading to engines using fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output allowed four large automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in operating costs than is estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the EU to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large car industries.

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

One independent energy policy specialist, who was not involved with the study, called the report a “highly valuable contribution” after years in which segments of the car sector claimed there was too little data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering that evidence.”