Plug-in Hybrid Cars Emit Nearly as Much as Gasoline Vehicles, Study Reveals

PHEVs emit nearly five times greater global warming emissions than lab-reported figures show, as per a recent report.

Widening Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel cars, based on analysis carried out by a non-profit organization. This contrasts significantly with lab tests, which suggested a 75% reduction in pollution.

Researchers studied data from onboard energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” stated a lead researcher participating in the study. “This discrepancy is widening and poses a serious issue. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric power relative to total mileage. They determined that just 27% of driving was done in EV mode, whereas lab estimates suggested 84%.

Additionally, when running in electric mode, pollution amounts were well above lab projections. This happened because EV motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning gasoline for almost a third of the distance completed in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled several large carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 extra per year in operating expenses than is estimated under lab tests.

“The strong statements that manufacturers often promote about their PHEV cars are obviously way off the truth,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have recently been drawn again into policy debates as carmakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large car manufacturing.

Several high-level officials have suggested PHEVs as a potential “compromise” option to include in the legislation.

An external energy policy specialist, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which segments of the automotive industry argued there was insufficient data to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme caution and in the light of that evidence.”