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Plug-in hybrid electric vehicles release almost five times greater global warming emissions than lab-reported figures indicate, as per a recent analysis.

Growing Gap Between Lab and Real-World CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel cars, according to research carried out by a advocacy group. This differs sharply with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts examined information from onboard fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” stated a lead researcher involved in the report. “That discrepancy is widening and creates a serious problem. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric mode relative to overall distance. They determined that just 27% of driving was completed in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in electric mode, pollution levels were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to operate independently, leading to engines burning gasoline for almost a third of the travel covered in EV mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in running costs than is estimated under lab conditions.

“The bold claims that manufacturers like to make about their PHEV cars are obviously way off the mark,” stated a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been brought back into political discussions as automakers have pressed the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large automotive manufacturing.

Some high-level politicians have proposed PHEVs as a potential “compromise” solution to include in the regulation.

One independent energy policy specialist, who was not involved with the study, described the report a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was too little information to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of this data.”