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Plug-in hybrid cars emit nearly five times more global warming emissions than official data show, according to a recent analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a advocacy group. That contrasts significantly with laboratory tests, which suggested a 75% reduction in pollution.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher participating in the report. “This gap is widening and creates a significant issue. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric power relative to total distance. The team determined that just 27% of travel was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when running in electric mode, emission amounts were well above lab projections. That occurred because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors burning gasoline for nearly one-third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled several large automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in operating costs than is estimated under laboratory tests.

“The bold claims that automakers often promote about their PHEV vehicles are clearly way off the truth,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little better than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have recently been drawn again into political discussions as carmakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from member states with significant automotive manufacturing.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to include in the legislation.

An external energy economics specialist, who was not involved with the research, described the analysis a “very useful addition” after a long period in which parts of the car sector argued there was insufficient data to properly evaluate actual emissions.

“These findings show, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or conventional cars,” they said. “Any policy adjustments concerning PHEVs should be implemented with utmost caution and in the light of this data.”