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

Plug-in hybrid cars produce almost 5x greater global warming emissions than official data show, according to a recent analysis.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy group. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” stated a lead researcher participating in the study. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to overall mileage. The team found that just 27% of travel was completed in EV mode, whereas official assumptions suggested 84%.

Even, when running in electric mode, pollution amounts were well above lab estimates. This happened because EV motors were not strong sufficient to operate alone, resulting to combustion motors using gasoline for almost one-third of the travel covered in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra annually in operating expenses than would be assumed under lab tests.

“The bold statements that automakers often promote about their PHEV vehicles are obviously far from the truth,” commented a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have recently been brought again into policy discussions as automakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with large car manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

An external energy policy expert, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little data to accurately assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they stated. “Any regulatory changes regarding PHEVs should be implemented with utmost care and in the light of this data.”