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PHEVs produce almost 5x greater global warming emissions than official data show, according to a recent analysis.

Growing Gap In Lab and Actual Emissions

Data reveals that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis carried out by a non-profit group. This contrasts significantly with lab tests, which assumed a 75% reduction in emissions.

Analysts examined information from onboard fuel consumption meters of 800,000 vehicles registered in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” stated a lead analyst participating in the report. “That gap is widening and creates a serious issue. As a result, PHEVs pollute nearly as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in electric power compared to total mileage. The team determined that just 27% of travel was completed in electric mode, while official estimates suggested over four-fifths.

Even, when operating in EV mode, pollution amounts were well above lab estimates. This happened because electric motors were insufficiently powerful enough to operate alone, resulting to engines using gasoline for almost one-third of the travel covered in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output allowed four large carmaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 more annually in running costs than is assumed under lab conditions.

“The bold statements 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 believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been drawn again into policy discussions as carmakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large car manufacturing.

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

One external energy policy expert, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the car sector claimed there was insufficient data to properly assess actual CO2 output.

“These findings demonstrate, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” the expert stated. “All policy changes concerning PHEVs should be made with utmost care and considering this data.”