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Plug-in hybrid cars produce almost 5x more global warming emissions than official data indicate, as per a recent analysis.

Growing Gap Between Official and Actual CO2 Output

Data shows that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. This differs significantly with lab estimates, which suggested a 75% decrease in pollution.

Analysts studied information from in-vehicle energy use meters of 800,000 cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, increased from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” stated a senior analyst participating in the study. “That discrepancy is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Factors Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric mode relative to total distance. The team found that just 27% of driving was done in electric mode, while lab estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were well above official estimates. That happened because electric motors were not strong sufficient to operate independently, resulting to engines using gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra annually in running expenses than would be estimated under lab conditions.

“The strong statements that automakers often promote about their PHEV vehicles are clearly way off the truth,” stated a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little better than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into political discussions as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car industries.

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

An external energy economics expert, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was too little data to accurately assess real-world CO2 output.

“These findings demonstrate, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be implemented with extreme caution and in the light of this evidence.”