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PHEVs emit nearly five times greater planet-heating pollution than lab-reported figures show, according to a recent report.

Growing Gap Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy group. This differs sharply with lab tests, which suggested a three-quarters decrease in emissions.

Researchers examined information from onboard energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a lead researcher involved in the report. “That gap is growing and creates a significant problem. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “utility factor” – the percentage of miles driven in electric power compared to overall mileage. The team determined that only 27% of driving was done in EV mode, while lab estimates assumed over four-fifths.

Even, when running in EV mode, pollution levels were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful enough to function independently, resulting to engines using gasoline for almost a third of the distance completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 more annually in operating expenses than would be assumed under laboratory tests.

“The bold statements that automakers often promote about their PHEV vehicles are clearly far from the mark,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into policy discussions as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from member states with large automotive manufacturing.

Some high-level politicians have proposed PHEVs as a possible “flexibility” option to introduce in the regulation.

One external energy policy expert, who was not involved with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry argued there was insufficient information to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional cars,” they said. “All regulatory adjustments concerning PHEVs should be made with extreme care and in the light of this data.”