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PHEVs emit almost 5x more planet-heating emissions than lab-reported figures show, as per a new report.

Widening Gap Between Official and Actual Emissions

Statistics shows that PHEVs release only 19% less CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy organization. This contrasts sharply with lab estimates, which suggested a 75% reduction in pollution.

Researchers studied data from in-vehicle energy use monitors of 800,000 cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” stated a lead analyst participating in the report. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the percentage of miles travelled in electric power relative to overall distance. They found that just a quarter of travel was done in EV mode, while official assumptions assumed 84%.

Even, when running in EV mode, emission amounts were well above lab estimates. This occurred because electric motors were not strong sufficient to operate independently, leading to combustion motors burning fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled four large carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 extra per year in operating costs than would be estimated under laboratory tests.

“The strong statements that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have recently been brought back into policy discussions as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with large automotive industries.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” solution to include in the legislation.

An independent energy policy expert, who was unaffiliated with the study, called the report a “very useful contribution” after years in which segments of the car sector claimed there was too little information to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap between official and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional cars,” they stated. “Any policy adjustments concerning PHEVs should be implemented with extreme caution and considering that data.”