Fuel Efficiency

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Fuel efficiency is the capacity to produce the greatest amount of work energy from the least
amount of fuel input. In vehicles, this is called fuel economy. Fuel economy arises from the
relationship between two types of energy: potential energy contained in a volume of fuel and kinetic energy associated with the vehicle’s motion. When a car burns fuel, the car’s potential energy decreases but its kinetic energy increases. Car designers try to design models that maximize this conversion so that most of the fuel’s potential energy turns into kinetic energy and little excess energy disappears as heat.

Improved fuel efficiency will come from two components: the type of vehicles produced
by car manufacturers and driving habits. Car engineers adjust the following characteristics to improve fuel efficiency: vehicle design, vehicle body’s materials, and engine design. Vehicle designs and materials that increase the car’s efficiency of movement help increase a car’s miles per gallon (MPG), which is the main value that describes fuel efficiency. Aerodynamic design, lightweight materials, and an efficient combustion system all combine to increase MPG. Meanwhile, drivers must do their part by following the advice of the U.S. Department of Energy (DOE) regarding fuel-efficient driving. The DOE has estimated that certain driving styles can save on fuel use by the percentages shown in the following list:

1. observe speed limits, 7–23 percent
2. avoid rapid acceleration and braking, 5–33 percent
3. avoid excessive idling
4. remove excess weight, 1–2 percent
5. use cruise control
6. use overdrive gears
7. keep engine tuned, 4 percent
8. replace dirty air filters, 10 percent
9. keep tires at recommended pressure, 3 percent
10. use vehicle’s recommended grade of motor oil, 1–2 percent
11. use trunk for storing items rather than roof rack, 1–2 percent
12. choose drive times to avoid peak congestion
13. combine trips
14. select vehicle based on fuel economy
15. buy a gas/alternative fuel hybrid car

All of the recommendations on this list cause few inconveniences for drivers and are easy adjustments to make. Drivers need only be willing to change their behavior in minor ways to help reduce harm to the environment and also save on their fuel expenses.