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

Growing Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs release just 19% lower CO₂ than conventional gas and diesel vehicles, according to research carried out by a advocacy group. This contrasts significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” said a senior researcher involved in the study. “That gap is growing and poses a serious issue. Consequently, PHEVs pollute nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode compared to total distance. They found that only 27% of travel was completed in electric mode, while lab estimates suggested 84%.

Additionally, when operating in electric mode, emission levels were significantly higher than lab projections. This occurred because electric motors were not strong sufficient to operate independently, leading to engines burning gasoline for nearly one-third of the travel covered in EV mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV emissions allowed four large automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 extra annually in operating expenses than would be estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid vehicles have lately been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant automotive industries.

Several high-level politicians have proposed plug-in hybrids as a potential “compromise” option to include in the legislation.

An external energy policy specialist, who was unaffiliated with the study, called the analysis a “very useful addition” after years in which segments of the automotive sector argued there was too little data to accurately assess real-world CO2 output.

“The results show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and in the light of that data.”