The light-duty transportation sector in Iran, as one of the main sources of greenhouse gas emissions, plays a significant role in increasing carbon dioxide (CO₂) levels and intensifying climate change. The sector’s heavy dependence on fossil fuels, outdated engine technologies, and the high carbon intensity of the power grid have led to a rising trend in emissions over recent decades.

The aim of this study is to analyze optimal decarbonization pathways for Iran’s light-duty vehicle fleet through 2050. To achieve this goal, time series modeling (Auto-ARIMA) and policy scenario simulations were conducted using the GAMS environment, in which five scenarios—ranging from “business as usual” to “optimistic policies”—were designed and examined.

The results indicate that if the current trend continues, the number of light vehicles in the country will exceed 50 million units by 2050, and CO₂ emissions will more than double. In contrast, under the optimistic scenario—which assumes an increase in the share of electric and hybrid vehicles to 20%, a 30% improvement in the fuel efficiency of combustion vehicles, and a reduction in the carbon intensity of the power grid from 0.60 to 0.40 kg CO₂ per kWh—total fleet emissions would decline by more than 30%.

The findings emphasize that achieving decarbonization targets requires comprehensive policies, including the development of clean technologies, reform of the power generation structure, fleet modernization, and the design of economic incentive mechanisms for users. These results can serve as a basis for national policymaking toward achieving sustainable and low-carbon transportation in Iran.