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

Widening Gap In Official and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, based on research conducted by a non-profit group. This contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Analysts examined data from onboard fuel consumption meters of 800,000 vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead researcher involved in the study. “That gap is widening and creates a serious issue. As a result, PHEVs emit nearly as much as petrol cars.”

Key Factors Driving the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in electric mode compared to total distance. They found that just 27% of driving was completed in EV mode, whereas official assumptions assumed 84%.

Additionally, when running in electric mode, emission amounts were well above official estimates. This occurred because electric motors were insufficiently powerful sufficient to function independently, leading to engines using gasoline for nearly a third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay about €500 more per year in operating expenses than would be assumed under laboratory tests.

“The strong claims that automakers often promote about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn again into policy debates as carmakers have pressed the European Union to relax CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with large car manufacturing.

Several high-level politicians have proposed PHEVs as a possible “compromise” option to introduce in the regulation.

One independent energy economics expert, who was not involved with the research, called the analysis a “highly valuable addition” after a long period in which segments of the automotive sector argued there was too little information to accurately assess real-world emissions.

“The results show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and considering that evidence.”