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PHEVs release almost 5x greater planet-heating emissions than lab-reported data show, as per a new report.

Widening Gap In Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit group. This differs sharply with lab estimates, which suggested a 75% decrease in pollution.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a senior researcher participating in the report. “That discrepancy is widening and poses a significant problem. As a result, PHEVs pollute nearly as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery mode compared to total mileage. The team found that only a quarter of travel was completed in EV mode, whereas lab assumptions suggested over four-fifths.

Even, when operating in EV mode, pollution levels were significantly higher than official projections. That happened because electric motors were not strong enough to operate alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in EV mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 more annually in operating costs than would be estimated under laboratory tests.

“The bold claims that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” commented a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Hybrid cars have recently been brought back into policy discussions as carmakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and opposition from EU countries with large automotive manufacturing.

Some high-level politicians have proposed plug-in hybrids as a potential “compromise” solution to include in the regulation.

An external energy economics specialist, who was unaffiliated with the study, called the report a “very useful contribution” after a long period in which parts of the automotive sector argued there was too little data to accurately assess real-world emissions.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” the expert said. “All policy changes concerning PHEVs should be implemented with utmost care and in the light of that data.”