The Indian traffic flow is diverse in nature, making it crucial to design and analyze the operation of different traffic facilities. Due to the mixed traffic with varying vehicle dimensions occupying the road space, it is difficult to make an accurate estimation of Passenger Car Units (PCUs). The objective of this study is to assess the impact of dimensions of the vehicles on speed, PCUs, and the capacity of the heterogeneous traffic. The data collection of the traffic was carried out at Varanasi, India, using a videographic technique at a mid-block section, and the dimensions of vehicles for the present-day road traffic were calculated by referring to automobile manufacturing company websites and vehicle sales brochures. The findings of the study indicate that the dimensions of the vehicles have a distinctive effect on the PCU factors of different categories of vehicles, when several modified approaches have been taken into account. The comparison between speed area ratio method and modified approach indicates a 9.742% variation in traffic capacity with respect to effective area and a 13.091% variation when the height of the vehicle, along with the effective area, is considered. Eventually, the comparative analysis by various approaches led to a detailed understanding of the present traffic scenario, which will be useful in comprehending the future expansion of the road capacity of the Indian nation.