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Plug-in hybrid electric vehicles produce nearly five times more global warming pollution than official data show, according to a recent analysis.

Growing Discrepancy Between Official and Actual CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy organization. This contrasts significantly with laboratory tests, which suggested a 75% reduction in emissions.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” stated a lead researcher involved in the report. “That discrepancy is growing and creates a significant problem. As a result, PHEVs emit almost as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in battery power relative to total distance. The team found that only a quarter of travel was completed in electric mode, while lab estimates suggested 84%.

Additionally, when operating in EV mode, emission amounts were well above official estimates. That happened because EV motors were not strong sufficient to operate independently, leading to combustion motors burning gasoline for almost one-third of the distance covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV emissions enabled several major automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in operating costs than is assumed under laboratory conditions.

“The bold statements that automakers like to make about their PHEV cars are obviously way off the truth,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid cars have lately been brought back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car industry and opposition from member states with large car manufacturing.

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

An external energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which parts of the car sector claimed there was too little data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of that data.”