Plug-in Hybrid Cars Emit Nearly as Heavily as Petrol Vehicles, Study Reveals

Plug-in hybrid cars emit nearly five times greater global warming pollution than official data indicate, according to a new analysis.

Widening Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, according to research conducted by a advocacy organization. This contrasts significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers studied data from in-vehicle fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a lead researcher involved in the report. “That discrepancy is growing and poses a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Key Factors Behind the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to total mileage. The team determined that only a quarter of driving was done in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in EV mode, pollution levels were well above official estimates. That happened because electric motors were not strong enough to function alone, resulting to combustion motors burning fossil fuels for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions enabled several major carmaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend approximately €500 extra per year in running expenses than is estimated under lab conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” commented a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Discussion and Industry Pressure

Hybrid cars have recently been drawn back into policy debates as carmakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the car sector and opposition from member states with significant automotive manufacturing.

Some high-level officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful contribution” after a long period in which segments of the automotive industry argued there was too little information to accurately evaluate actual emissions.

“These findings show, without question, that the difference in official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or diesel cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be made with extreme care and in the light of this data.”