At present, increased fuel consumption and air pollution are major problems in heavy traffic conditions where engines run at idle speed. Although some modern vehicles have automatic idle stop technology to reduce fuel consumption and emissions, a wide range of older vehicles still lack this feature. Drivers often face the decision of whether to keep the engine idling or switch off the engine and restart it during traffic stops. This study experimentally investigates fuel consumption of conventional gasoline-powered vehicles under various driving patterns by analyzing vehicle performance during starting and idling. Mass Air Flow (MAF) sensor data were collected using a LAUNCH OBD-II scanner connected to a Toyota 1NZ-FE, 1500CC, four-cylinder inline liquid-cooled engine under an operating temperature range of 85-95°C. Considering multiple start-idling-stop tests, MAF values were plotted against time to calculate the air-flow rate during starting and idling. The average fuel masses were obtained using the starting air–fuel ratio 13:1 and idling air–fuel ratio 14.7:1. Based on the results, the starting fuel consumption was 0.380g, and the idling fuel consumption rate was 0.123g/s. Ultimately, if the engine is idling for more than 3.07s, it starts wasting fuel. This analysis is purely based on fuel consumption and emissions, neglecting air conditioning, battery charging and other auxiliary functions. Based on the results, it is more fuel efficient and environmentally friendly to stop and restart the engine if the vehicle is required to stop for more than 3.1s due to urban traffic conditions. Furthermore, this study should be extended considering secondary factors such as starter motors, battery wear, etc. These findings contribute to reducing urban air pollution due to CO, CO2, NOx, improving fuel efficiency, and aiming to develop a suitable unit for vehicles that do not have the factory-fitted idle stop function.