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PHEVs release nearly five times more planet-heating emissions than lab-reported figures show, as per a new report.

Growing Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. This contrasts sharply with lab estimates, which suggested a 75% decrease in pollution.

Researchers studied information from onboard energy use meters of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a senior researcher participating in the report. “That gap is growing and creates a serious issue. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode compared to overall distance. The team found that only 27% of travel was done in electric mode, while official assumptions suggested 84%.

Even, when operating in electric mode, emission levels were well above lab estimates. This occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines burning gasoline for almost one-third of the travel covered in electric mode.

Policy and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled four major automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra annually in running costs than would be estimated under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have lately been drawn again into political discussions as automakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a potential “flexibility” solution to include in the regulation.

An independent energy economics expert, who was not involved with the research, described the analysis a “highly valuable addition” after years in which parts of the car sector argued there was too little information to properly assess real-world emissions.

“The results show, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “All regulatory adjustments concerning PHEVs should be made with extreme care and considering that data.”