Plug in Hybrid Cars Pollute Almost as Heavily as Petrol Vehicles, Report Reveals

Plug-in hybrid cars emit nearly five times more planet-heating pollution than lab-reported data show, according to a recent analysis.

Growing Gap Between Lab and Actual Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to research conducted by a non-profit organization. That differs sharply with lab tests, which assumed a three-quarters decrease in emissions.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a senior analyst involved in the report. “That gap is widening and creates a serious problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power compared to total distance. The team determined that just 27% of travel was done in EV mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors using gasoline for almost a third of the travel completed in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 extra annually in running expenses than would be estimated under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn again into policy discussions as carmakers have lobbied the EU to relax CO₂ standards. A proposed ban on new combustion engine cars in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant automotive manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “compromise” option to include in the legislation.

One external energy policy expert, who was not involved with the study, described the analysis a “very useful contribution” after a long period in which parts of the automotive industry argued there was insufficient information to accurately evaluate actual emissions.

“These findings show, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they said. “All regulatory adjustments concerning PHEVs should be made with utmost care and considering that evidence.”