Plug-in Hybrid electric Cars Pollute Almost as Much as Gasoline Cars, Report Reveals

PHEVs emit almost 5x more global warming emissions than lab-reported data show, according to a new analysis.

Widening Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on research carried out by a non-profit organization. That differs significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers studied information from onboard energy use monitors of 800,000 cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported figures are falling,” stated a lead analyst involved in the study. “This discrepancy is growing and poses a serious issue. As a result, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power relative to total mileage. The team found that just 27% of driving was completed in electric mode, whereas official assumptions suggested 84%.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. That happened because electric motors were not strong enough to function alone, leading to engines burning fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four major carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ standards.

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

“The strong claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the environment and saving money. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into policy discussions as automakers have pressed the European Union to relax CO₂ standards. A proposed ban on new combustion engine vehicles in 2035 has faced intense lobbying from the car sector and opposition from member states with large car industries.

Some senior officials have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

An external energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient data to accurately evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they stated. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that data.”