Driving Conditions: Fuel consumption has several other variables, one of which is driving conditions; idling through hundreds of stop lights daily in the city obviously takes more fuel to move a car than cruising on a smooth highway at a constant speed. Increased traffic flow and shorter trips will cause a vehicle to burn more fuel.
Driving Style: Aggressive driving can easily reduce gas mileage by half. Gentle driving gets better mileage.
Performance: A cleaner engine works more efficiently. Your high-performance car will need regular service and timely replacement of worn parts to keep its fuel economy advantages tapped.
Fuel Quality: This can affect the performance and efficiency of an engine. High-quality fuel means better combustion, which leads to great mileage as well.