Enter the total number of gallons of gas a car can hold and the total mileage it can travel with a full tank to determine the fuel efficiency.

## Fuel Efficiency Formula

The following formula is used to calculate the fuel efficiency of a car.

E = TM / TG

• Where E is the fuel efficiency (miles per galon) (mpg)
• TM is the total miles traveled on one tank of gas
• TG is the total gallons of gas held by a full tank

## Fuel Efficiency Definition

Fuel efficiency is defined as the total miles per gallon of fuel that a car can travel. Fuel efficiency is used to describe how efficiently a car takes fuel and converts it into movement.

## How to calculate fuel efficiency?

Example Problem #1:

First, determine the total gallons the car can hold. For this example, the car holds 20 gallons of gasoline as fuel.

Next, drive the car from full all the way to empty and record the distance. In this problem, the car traveled 300 miles.

Finally, calculate the fuel efficiency using the formula:

E = TM / TG

= 300 / 20

= 15 MPG.

Example #2:

In this next example, we are looking at a much bigger vehicle that can hold 40 gallons of gas.

On that 40 gallons of gas, the car is able to drive for 500 miles.

Using the formula, the fuel efficiency is calculated as:

E = TM / TG

= 500/40

= 12.5 miles per gallon

Even though this car could hold more fuel, it was still less efficient than the first car.