Save 10% to 40% by avoiding speeding and aggressive accelerating and braking.
Each 5 mph you drive over 50 mph can lower gas mileage by 7% or more.
Fixing an out-of-tune engine can improve its efficiency by 4% on average.
A roof-top cargo box can reduce fuel economy from 2% to 17%.
Using the wrong grade of motor oil can lower mileage by 1% to 2%.
An extra 100 pounds can lower gas mileage by about 1%.
Idling can use a quarter to a half gallon of fuel per hour. Turn off your engine when you are stopped and not in traffic.
Under-inflated tires can lower gas mileage by 0.3% for every 1 psi drop in pressure of all four tires.
You'll drive fewer miles and drive less while the engine is cold and inefficient.
It helps you maintain a constant speed, which can save gas.