How to Compare the Gas Mileage of Automobiles

When buying a car, one of the factors most people examine closely is fuel efficiency. When comparing gas mileage of different vehicles, buyers must take into consideration both the highway and the city efficiency. In addition, different people will use cars for different purposes, so the number of miles the car is driven and what type of miles are driven will also affect the amount of money drivers will spend on gas.

Instructions

1

Use the Department of Energy's online database (see link in the Resource section) or another database to look up the gas mileage of the cars you are comparing.

2

Predict the number of miles you drive per year.

3

Estimate the percentage of miles you drive in the city versus the highway. For example, if you expect most of your driving to be transporting the kids around town, perhaps 80 percent would be city driving and 20 percent would be highway driving.

4

Calculate the number of miles you will drive in the city and on highways annually by multiplying the number of miles (from Step 2) by the percentage you calculated in Step 3. For example, if you expect to drive 10,000 miles each year, with 80 percent being city miles, you would expect to drive 8,000 city miles and 2,000 highway miles.

5

Calculate the number of gallons of gas that would be required to cover the distances found in Step 4 for each car by dividing the number of miles by the number of miles per gallon (MPG) for each vehicle you're considering. For example, if car A receives 30 MPG on the highway and 20 miles per gallon in the city, you would divide 8,000 by 20 to get 400 gallons and 2,000 by 30 to get about 67 gallons, for an annual total of 467 gallons. If car B gets 28 MPG on the highway and 22 MPG in the city, you would divide 8,000 by 22 to get about 364 gallons and 2,000 by 28 to get about 71 gallons, for an annual total of 435 gallons.

6

Calculate how many gallons the more efficient car would save you per year by subtracting the number of gallons of the more efficient car from the number of gallons for the less efficient car. In this example, you would subtract 435 from 467 to find that car B would save you about 32 gallons per year.