Plug in Hybrid electric Vehicles Pollute Almost as Much as Gasoline Cars, Study Finds

PHEVs emit almost 5x more planet-heating emissions than official data show, as per a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a non-profit group. This differs sharply with laboratory estimates, which assumed a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a lead researcher participating in the report. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Key Factors Driving the Discrepancy

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric mode compared to total distance. The team found that only a quarter of travel was done in EV mode, while lab estimates assumed 84%.

Additionally, when running in electric mode, emission amounts were well above official estimates. That occurred because electric motors were insufficiently powerful enough to function alone, leading to engines burning gasoline for nearly a third of the travel completed in electric mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output allowed several large automaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 more per year in operating expenses than would be estimated under laboratory conditions.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive industry and opposition from member states with significant car manufacturing.

Several high-level politicians have suggested PHEVs as a possible “flexibility” option to introduce in the legislation.

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

“These findings show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme care and in the light of that data.”