U.S. Department of Energy suggestions for increasing gas mileage include proper car maintenance, using efficient driving methods, organizing trips in advance and purchasing a fuel-efficient vehicle, such as a hybrid or electric vehicle. Choice of vehicle is a major factor that contributes to fuel efficiency.
To help improve gas mileage, the car's engine should be well tuned, and tires should be inflated to the tire pressure indicated in the owner's manual. Using only the grade of motor oil suggested by the car's manufacturer is also important.
Because accelerating, braking quickly and speeding increase gas consumption, driving within the speed limit is one method of efficient driving. Using the car's cruise control on the highway can help a driver remain within the speed limit and increase gas mileage. Efficient driving also includes not hauling items on the car's roof and not driving with heavy items inside the car. Allowing the engine to idle when parked is also not recommended. Plan errands in advance so that travel is done in longer trips while the car's engine is already warm. This is a more efficient use of fuel than making multiple short trips that start with a cold engine. Additionally, driving during rush hour should be avoided when possible.