Plug-in Hybrid electric Vehicles Emit Almost as Much as Gasoline Vehicles, Study Reveals

Plug-in hybrid cars produce nearly 5x greater global warming pollution than lab-reported figures indicate, according to a recent analysis.

Widening Gap In Official and Real-World Emissions

Data shows that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. That contrasts sharply with lab tests, which suggested a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars sold in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” said a lead researcher participating in the study. “This discrepancy is widening and poses a serious problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode compared to overall mileage. The team determined that only 27% of driving was completed in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official projections. That happened because EV motors were not strong sufficient to operate independently, leading to engines using fossil fuels for almost a third of the travel covered in EV mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV emissions enabled several major automaker groups to escape more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 extra per year in operating expenses than is estimated under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid cars are clearly way off the truth,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with large car industries.

Some senior officials have proposed PHEVs as a potential “flexibility” solution to include in the regulation.

An independent energy economics specialist, who was not involved with the research, called the analysis a “very useful addition” after a long period in which parts of the automotive industry argued there was too little information to properly assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel cars,” the expert stated. “All policy changes regarding PHEVs should be made with extreme caution and in the light of that data.”