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Plug-in hybrid cars release almost five times more planet-heating emissions than official figures indicate, as per a recent report.

Growing Gap In Official and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit organization. That differs significantly with laboratory tests, which suggested a 75% reduction in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official figures are falling,” stated a lead analyst involved in the report. “This gap is widening and creates a significant issue. As a result, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in electric mode compared to overall mileage. They determined that only a quarter of driving was done in electric mode, whereas lab assumptions suggested 84%.

Even, when operating in EV mode, emission levels were well above lab projections. That happened because EV motors were not strong sufficient to function independently, resulting to engines using fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed several major carmaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend about €500 extra per year in running expenses than would be assumed under lab tests.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have recently been drawn again into political debates as automakers have pressed the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car industries.

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

One independent energy policy expert, who was not involved with the research, described the analysis a “very useful addition” after a long period in which parts of the car industry argued there was too little information to accurately assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional cars,” they said. “All regulatory changes concerning PHEVs should be implemented with utmost caution and considering that evidence.”