The relationship between gallons used over a given distance and miles per gallon (mpg) is not linear. Trading a low-mpg car or truck for one with just slightly better mpg will save more fuel than trading a high-mpg car or truck for one that is even higher. An improvement in fuel economy by 5 mpg does not translate to a constant fuel savings amount. For example, trading a truck that gets 10 mpg for a new one that gets 15 mpg will save 33 gallons of fuel for every 1,000 miles driven. In contrast, trading a 30-mpg car for a new car that gets 35 mpg will save 5 gallons of fuel for every 1,000 miles driven.
Fuel Use versus Fuel Economy
Note: Each category on the horizontal axis shows a five-mile per gallon improvement in fuel economy.
|Fuel Economy (Miles per Gallon)||Gallons Per 1,000 Miles||If you have a car with this fuel economy||And you trade it for a car with this fuel economy||You save this many gallons for every 1,000 miles you drive|
Source: Oak Ridge National Laboratory, 2015 Vehicle Technologies Market Report, ORNL/TM-2016/124, April 2016, Figure 4.