Plug-in Hybrid Vehicles Emit Nearly as Much as Gasoline Cars, Study Reveals

PHEVs produce nearly 5x greater planet-heating emissions than lab-reported figures indicate, according to a new report.

Widening Gap In Official and Actual CO2 Output

Data reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. That differs sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Researchers examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” stated a senior researcher participating in the study. “That gap is widening and creates a significant issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power compared to total distance. They determined that just a quarter of travel was completed in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to operate alone, resulting to engines using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major automaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend about €500 more annually in operating expenses than is estimated under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have lately been drawn again into policy discussions as carmakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with significant automotive manufacturing.

Some high-level politicians have suggested plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

One independent energy economics expert, who was not involved with the research, called the analysis a “highly valuable addition” after a long period in which parts of the automotive sector claimed there was too little information to properly assess real-world emissions.

“The results demonstrate, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with extreme caution and considering this evidence.”