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PHEVs release nearly five times greater global warming pollution than lab-reported figures show, as per a recent analysis.

Growing Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy group. That differs sharply with laboratory tests, which suggested a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption meters of 800,000 vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a lead researcher participating in the study. “That discrepancy is widening and creates a significant problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to total distance. They found that just 27% of driving was done in electric mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab projections. This occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV emissions enabled four large carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 more per year in running costs than is assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into policy debates as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the car sector and resistance from member states with significant car industries.

Several senior politicians have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the legislation.

An independent energy policy expert, who was not involved with the research, described the report a “very useful addition” after a long period in which parts of the automotive industry claimed there was too little data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional vehicles,” they said. “Any policy changes regarding PHEVs should be made with utmost caution and considering this evidence.”