This study presents a comprehensive gridded emission inventory (EI) for India’s road transport sector tailpipe emissions for the year 2021, estimating emissions of PM2.5, NOx, and SO2. The inventory incorporates vehicle volume-weighted emission factors in the development of the inventory. Vehicle technology advancements and fuel consumption trends were integrated to improve accuracy. Uttar Pradesh emerged as the highest emitter of PM2.5 due to its large population and fuel consumption, while Maharashtra, driven by its high gross domestic product and urbanization, ranked second. Among metropolitan cities, Mumbai reported the highest PM2.5 emissions from the transport sector. The total emissions for 2021 were estimated at 307 Kt of PM2.5, 2,175 Kt of NOx, and 35 Kt of SO2. Comparative analyses with other inventories, including EDGAR, ECLIPSE, and TERI, confirmed the reliability of the results, with uncertainties aligning with ranges reported in previous studies. However, scenario analyses indicate limited emission reductions in the transport sector due to the slow adoption of electric vehicles. These findings provide actionable insights for policymakers to prioritize emission control strategies and support the success of the National Clean Air Program (NCAP). By identifying significant emission sources and their spatial distribution, this study offers a robust foundation for source apportionment studies and targeted policy interventions.