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Plug-in hybrid cars emit almost 5x greater global warming emissions than official figures show, as per a new analysis.

Growing Discrepancy In Lab and Actual CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. This differs significantly with lab tests, which assumed a 75% reduction in emissions.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” said a senior researcher involved in the report. “This discrepancy is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery power relative to overall mileage. They found that only 27% of travel was done in electric mode, while lab assumptions assumed 84%.

Even, when running in electric mode, pollution levels were significantly higher than official projections. This happened because electric motors were not strong sufficient to operate alone, leading to engines using fossil fuels for nearly a third of the travel covered in EV mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several major automaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay about €500 extra annually in operating expenses than would be estimated under laboratory conditions.

“The strong claims that automakers like to make about their PHEV vehicles are obviously way off the truth,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid cars have lately been drawn again into political debates as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large automotive manufacturing.

Several senior politicians have suggested PHEVs as a possible “compromise” solution to introduce in the regulation.

One external energy economics specialist, who was not involved with the research, described the report a “very useful addition” after years in which segments of the automotive industry argued there was too little information to accurately evaluate real-world CO2 output.

“These findings demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” they said. “All regulatory adjustments concerning PHEVs should be made with utmost care and in the light of that evidence.”