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PHEVs release almost five times greater global warming emissions than official figures show, according to a recent analysis.

Growing Gap Between Official and Actual CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel cars, according to analysis conducted by a non-profit organization. That contrasts sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts studied data from onboard fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” said a senior analyst involved in the study. “This gap is widening and creates a significant problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to total mileage. They found that only 27% of driving was done in EV mode, while lab assumptions suggested 84%.

Even, when running in electric mode, emission levels were well above lab estimates. This occurred because electric motors were not strong sufficient to function independently, leading to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed several major automaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating costs than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into policy discussions as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant automotive industries.

Several high-level politicians have proposed plug-in hybrids as a possible “flexibility” solution to include in the regulation.

An external energy economics expert, who was unaffiliated with the research, called the report a “very useful contribution” after a long period in which segments of the automotive industry claimed there was insufficient data to properly assess actual emissions.

“The results demonstrate, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and considering that data.”