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Plug-in hybrid electric vehicles emit nearly 5x greater planet-heating pollution than lab-reported data indicate, as per a new analysis.

Widening Gap In Official and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a non-profit organization. This contrasts significantly with laboratory tests, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” stated a senior researcher involved in the study. “That discrepancy is widening and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the percentage of miles driven in electric mode relative to total distance. They determined that only a quarter of driving was completed in EV mode, whereas official assumptions suggested over four-fifths.

Even, when running in EV mode, pollution levels were well above official estimates. This occurred because EV motors were insufficiently powerful enough to operate independently, resulting to engines using fossil fuels for almost one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four large automaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 more per year in running expenses than would be assumed under laboratory tests.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been drawn again into political debates as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from member states with significant automotive manufacturing.

Several senior officials have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An external energy economics expert, who was unaffiliated with the research, described the report a “very useful contribution” after a long period in which segments of the automotive industry claimed there was too little information to accurately assess actual emissions.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” they said. “All regulatory changes regarding PHEVs should be implemented with extreme caution and considering this evidence.”