Plug-in Hybrid Vehicles Pollute Almost as Much as Gasoline Vehicles, Report Finds

Plug-in hybrid cars produce almost 5x more planet-heating emissions than official data indicate, according to a recent report.

Widening Discrepancy Between Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel cars, based on research carried out by a advocacy organization. That differs significantly with lab tests, which assumed a 75% reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” said a lead analyst participating in the study. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery power compared to overall distance. They found that just 27% of driving was completed in electric mode, while lab estimates assumed 84%.

Even, when operating in electric mode, pollution amounts were well above lab projections. This happened because electric motors were insufficiently powerful enough to function alone, leading to combustion motors burning fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output enabled four major automaker companies to escape over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 extra annually in operating costs than is estimated under laboratory tests.

“The bold statements that automakers like to make about their PHEV vehicles are clearly way off the mark,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of energy consumption, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with significant car manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

An external energy policy specialist, who was not involved with the research, described the report a “very useful addition” after years in which segments of the automotive sector claimed there was insufficient information to properly assess actual emissions.

“These findings show, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or conventional cars,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and considering that data.”