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PHEVs release nearly five times greater planet-heating emissions than official figures indicate, as per a recent report.

Growing Gap Between Official and Actual CO2 Output

Data shows that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. That differs significantly with lab tests, which suggested a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” stated a lead researcher participating in the study. “This gap is growing and creates a significant issue. Consequently, PHEVs emit almost as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the ratio of miles travelled in electric mode relative to overall mileage. They found that just 27% of travel was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, emission amounts were well above lab projections. That happened because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines using gasoline for nearly one-third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed several large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

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

“The strong statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” stated a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have recently been brought back into political debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with significant automotive industries.

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

An independent energy economics expert, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which parts of the car sector claimed there was too little data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel cars,” they stated. “All regulatory changes concerning PHEVs should be implemented with utmost care and in the light of that data.”