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PHEVs release nearly 5x more planet-heating emissions than official data show, according to a new report.

Widening Gap Between Official and Actual CO2 Output

Statistics reveals that PHEVs emit just 19% less CO₂ than traditional gas and diesel vehicles, according to research carried out by a advocacy organization. This differs significantly with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a senior analyst involved in the report. “That gap is widening and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Researchers linked most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to total mileage. They found that just 27% of travel was done in EV mode, while lab estimates assumed over four-fifths.

Even, when running in EV mode, pollution levels were well above lab estimates. That happened because EV motors were insufficiently powerful enough to function independently, leading to combustion motors burning fossil fuels for nearly a third of the distance completed in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions enabled several large automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

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

“The strong statements that automakers often promote about their PHEV vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Industry Pressure

Hybrid cars have recently been drawn back into policy discussions as automakers have lobbied the European Union to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant car manufacturing.

Several high-level officials have suggested PHEVs as a potential “compromise” solution to include in the regulation.

One independent energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the automotive industry claimed there was too little information to properly evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or conventional cars,” they stated. “Any policy changes concerning PHEVs should be made with utmost care and in the light of this data.”