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PHEVs produce almost 5x more planet-heating pollution than lab-reported data show, according to a recent report.

Widening Discrepancy Between Official and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. This differs significantly with lab estimates, which assumed a 75% decrease in emissions.

Analysts examined information from onboard energy use meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team found 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.

“Real-world CO2 output are increasing, while lab-reported figures are falling,” said a senior analyst participating in the study. “This discrepancy is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in electric power relative to overall distance. They found that just 27% of driving was completed in EV mode, while official assumptions suggested over four-fifths.

Even, when running in EV mode, pollution amounts were well above official estimates. This occurred because EV motors were not strong enough to function alone, resulting to engines using gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 extra annually in running expenses than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their PHEV cars are obviously far from the mark,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have lately been brought back into political debates as carmakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant automotive manufacturing.

Several senior officials have suggested PHEVs as a potential “flexibility” solution to include in the regulation.

An independent energy policy expert, who was not involved with the study, called the report a “highly valuable contribution” after years in which segments of the automotive industry claimed there was too little data to accurately evaluate real-world emissions.

“The results demonstrate, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost caution and considering that data.”