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PHEVs release nearly five times more planet-heating pollution than lab-reported data indicate, as per a new report.

Widening Discrepancy Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit organization. That contrasts significantly with lab tests, which suggested a three-quarters reduction in pollution.

Researchers examined information from onboard fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total distance. They determined that only a quarter of driving was done in electric mode, whereas official assumptions suggested over four-fifths.

Additionally, when running in EV mode, pollution levels were well above lab estimates. That occurred because EV motors were not strong enough to function alone, resulting to engines using gasoline for nearly one-third of the travel covered in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV emissions enabled several major automaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in running costs than would be assumed under lab conditions.

“The strong statements that automakers often promote about their plug-in hybrid vehicles are clearly way off the truth,” commented a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought again into political discussions as automakers have lobbied the EU to relax CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large car manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An external energy economics specialist, who was not involved with the study, described the analysis a “highly valuable addition” after years in which parts of the car industry claimed there was too little data to accurately assess actual emissions.

“These findings demonstrate, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or diesel cars,” they said. “All policy adjustments concerning PHEVs should be implemented with extreme care and considering this evidence.”