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PHEVs release almost 5x greater planet-heating pollution than official figures show, as per a recent analysis.

Growing Discrepancy In Official and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. That contrasts significantly with lab tests, which assumed a 75% reduction in emissions.

Analysts studied data from onboard fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” said a senior researcher involved in the report. “This discrepancy is growing and poses a serious problem. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in electric power compared to overall mileage. They found that only a quarter of travel was completed in electric mode, while official assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were well above official estimates. This happened because electric motors were not strong sufficient to operate alone, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Consequences

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

Furthermore, drivers of PHEVs could spend about €500 more annually in operating costs than would be estimated under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and resistance from EU countries with significant automotive industries.

Several senior politicians have suggested plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One external energy economics expert, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the automotive sector claimed there was too little data to properly assess real-world emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel cars,” the expert stated. “All policy changes regarding PHEVs should be made with utmost care and considering that evidence.”