Determining fuel efficiency between fill-ups involves estimating the number of miles traveled per gallon of fuel consumed within a specified period, without requiring a full tank at either the beginning or end of the measurement. This calculation uses the miles driven as indicated by the odometer or trip meter, divided by the gallons of fuel added during the measurement period. For example, if a vehicle travels 300 miles and consumes 10 gallons of fuel, the miles per gallon (MPG) is 30.
This method offers a practical approach to tracking fuel consumption under real-world driving conditions. It allows for ongoing monitoring of vehicle performance, potentially identifying issues that could affect fuel economy, such as tire pressure, driving habits, or mechanical problems. Historically, drivers relied on similar estimations to gauge the efficiency of their vehicles, adapting their routes and driving styles to minimize fuel usage long before the advent of sophisticated on-board computer systems.