Get Rid of Unnecessary Weight

Avoid keeping unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your MPG by 2% or more for small cars. A roof rack or carrier provides additional cargo space and may allow you to meet your needs with a smaller car. However, a loaded roof rack can decrease your fuel economy by 5%. Reduce aerodynamic drag and improve your fuel economy by placing items inside the trunk whenever possible.
 
Learn more at Fuel Economy.gov