In order to evaluate and improve the fuel utilization efficiency of gasoline-powered vehicle, the vehicle energy flow test was conducted on chassis dynamometer under the NEDC of cold starting. Based on the tested data, the vehicle energy balance was built under the whole NEDC. Research results show that the distributions of various kinds of energy flow were largely influenced by vehicle operating conditions. Apart from idling conditions, the brake thermal efficiency of internal combustion engine (ICE) is mainly between 10% and 35%. At the initial stage of NEDC, the brake thermal efficiency is very low due to the cold starting. Under urban driving cycle (UDC), the percentage of pumping loss is usually below 10%, and under extra urban driving cycle (EUDC), it further decreases and even approaches to zero. The exhaust gas energy flow is mainly influenced by the mass flow rate of exhaust gas, while its percentage in total fuel energy depends largely on exhaust gas temperature. In general, the coolant energy flow is less sensitive to the ICE operating conditions, but its percentage fluctuates wildly under the transient conditions of NEDC. In most cases, the percentage of ICE coolant energy flow is between 13% and 35% with dramatic fluctuations, and the sudden deceleration of vehicle causes the generation of sharp peaks of the percentages of pumping loss and coolant energy flow.