Plug-in Hybrid Vehicles Pollute Almost as Heavily as Gasoline Vehicles, Study Reveals

PHEVs produce almost five times greater planet-heating pollution than official figures show, according to a recent report.

Growing Gap In Lab and Real-World Emissions

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a non-profit organization. That contrasts significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” stated a lead analyst involved in the study. “This gap is growing and creates a significant issue. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to total mileage. The team determined that just 27% of travel was done in EV mode, while official estimates suggested over four-fifths.

Even, when operating in electric mode, pollution levels were well above official projections. That happened because electric motors were not strong enough to function independently, leading to engines burning gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV emissions allowed several large carmaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra per year in running expenses than is estimated under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with significant car manufacturing.

Several senior officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An independent energy policy expert, who was not involved with the study, called the analysis a “highly valuable addition” after years in which parts of the car sector claimed there was insufficient data to properly assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “Any regulatory changes regarding PHEVs should be implemented with utmost care and in the light of that evidence.”