Vehicle fuel consumption is presented via mathematical modeling for urban operating conditions. Vehicle fuel consumption is calculated separately for four modes: average speed, accelerations, decelerations, and at idling mode. This approach was chosen since a significant part of fuel consumption at urban conditions occurs at decelerations and idling mode. In each of these modes fuel consumption is calculated based on engine efficiency. Unlike previously developed models, which determine fuel consumption based on constant specific fuel consumption, ours determines fuel consumption based on engine efficiency, which makes the model more adequate since it incorporates engine mode changes. The engine efficiency is expressed as a function of speed mode and engine power utilization degree. It is illustrated how the effect of various design parameters on vehicle fuel consumption can be studied utilizing the suggested model. During deceleration, although in practice there is no need for energy, the engine continues to consume fuel. This process must be reflected in the calculations. In this work we do take in to account this process in our calculations. By our calculations it is shown that 31% of the fuel consumed is at idling mode and 6% of the fuel consumption is at deceleration mode. For a more detailed analysis we carried out calculations of the time and other parameters for the different modes of urban cycle (ECE-15 driving cycles). It is shown that simulations based on the proposed model enable one to study the influence of operating conditions and constructive parameters on fuel consumption.
