Plug-in Hybrid electric Cars Emit Nearly as Much as Petrol Vehicles, Report Finds

Plug-in hybrid electric vehicles emit almost 5x greater planet-heating emissions than lab-reported data show, as per a new report.

Growing Discrepancy Between Official and Actual CO2 Output

Data reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a advocacy group. That contrasts sharply with lab tests, which assumed a 75% reduction in emissions.

Researchers examined information from in-vehicle fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” stated a senior researcher participating in the study. “That discrepancy is widening and creates a serious issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode relative to overall distance. They found that only a quarter of driving was completed in EV mode, while official assumptions suggested over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than lab estimates. That happened because EV motors were not strong sufficient to function alone, resulting to combustion motors burning gasoline for nearly a third of the distance completed in electric mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed four major carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 extra annually in operating costs than would be estimated under lab conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a automotive analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been brought back into policy discussions as automakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with significant automotive manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” solution to include in the regulation.

One external energy policy expert, who was unaffiliated with the study, described the report a “very useful contribution” after years in which parts of the automotive industry argued there was insufficient information to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is significantly larger than for petrol or conventional vehicles,” they stated. “All policy changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”