Plug in Hybrid Vehicles Emit Almost as Heavily as Gasoline Vehicles, Study Finds

PHEVs produce nearly 5x more planet-heating emissions than lab-reported figures show, according to a recent analysis.

Widening Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy group. This differs significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “That gap is growing and creates a serious issue. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to overall mileage. They found that only 27% of driving was completed in electric mode, whereas lab assumptions assumed 84%.

Even, when running in EV mode, emission amounts were well above official estimates. That happened because EV motors were not strong sufficient to function alone, resulting to engines burning gasoline for nearly one-third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled four large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

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

“The bold statements that automakers often promote about their PHEV vehicles are clearly far from the truth,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Pressure

Plug-in hybrid cars have recently been brought back into political discussions as automakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from member states with significant car manufacturing.

Some high-level politicians have suggested PHEVs as a potential “compromise” solution to include in the legislation.

One external energy economics expert, who was not involved with the study, called the analysis a “highly valuable contribution” after years in which parts of the car industry argued there was insufficient information to properly assess real-world emissions.

“The results demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional cars,” the expert stated. “All policy changes regarding PHEVs should be implemented with utmost care and in the light of that data.”