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PHEVs emit almost 5x greater planet-heating pollution than lab-reported figures indicate, as per a new analysis.

Growing Gap In Lab and Actual Emissions

Statistics reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. This contrasts significantly with lab estimates, which assumed a 75% decrease in emissions.

Researchers examined data from onboard energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a senior analyst participating in the study. “That discrepancy is widening and creates a significant issue. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total distance. The team found that just 27% of driving was done in EV mode, whereas lab assumptions assumed over four-fifths.

Even, when operating in electric mode, emission amounts were well above official projections. That occurred because EV motors were not strong sufficient to operate independently, resulting to combustion motors using gasoline for almost a third of the travel completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several large carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in running expenses than is estimated under laboratory tests.

“The strong claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into political debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with large automotive manufacturing.

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

One external energy economics expert, who was not involved with the study, described the report a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” the expert said. “All policy changes regarding PHEVs should be made with extreme caution and considering that data.”