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Plug-in hybrid cars release nearly five times more planet-heating emissions than lab-reported figures indicate, as per a new analysis.

Growing Gap Between Official and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit organization. This differs significantly with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers examined data from onboard energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are falling,” stated a senior analyst participating in the report. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric power relative to overall distance. The team determined that just 27% of driving was done in electric mode, whereas official assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were well above official estimates. That happened because electric motors were not strong enough to operate alone, resulting to combustion motors using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output enabled several major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 more per year in operating costs than is assumed under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into policy debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with large car industries.

Some high-level politicians have suggested PHEVs as a potential “flexibility” option to introduce in the regulation.

An independent energy economics specialist, who was not involved with the research, called the report a “highly valuable contribution” after years in which segments of the car industry claimed there was insufficient information to properly assess actual emissions.

“The results show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional cars,” the expert said. “All regulatory changes regarding PHEVs should be implemented with extreme caution and considering this evidence.”