🔗 Share this article

Plug-in hybrid cars produce almost 5x more planet-heating pollution than lab-reported figures show, according to a new report.

Growing Discrepancy In Official and Actual Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a advocacy organization. That contrasts significantly with lab tests, which suggested a 75% reduction in pollution.

Analysts studied data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a senior analyst participating in the report. “This gap is growing and poses a significant issue. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to total distance. The team determined that just a quarter of travel was completed in electric mode, whereas lab assumptions assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above lab estimates. This occurred because electric motors were insufficiently powerful enough to function alone, resulting to engines using fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV emissions enabled several major automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in operating costs than is assumed under laboratory tests.

“The bold claims that automakers often promote about their PHEV vehicles are obviously far from the mark,” stated a transport analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy debates as automakers 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 car sector and resistance from member states with significant automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An external energy policy specialist, who was not involved with the study, described the report a “very useful addition” after years in which segments of the automotive sector argued there was too little data to accurately assess actual CO2 output.

“The results show, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel cars,” they said. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and in the light of this evidence.”