A five-cylinder Hummer H3 gets an estimated 14 miles-per-gallon in the city and 18 on the highway. An eight-cylinder engine gets an estimated 13 miles-per-gallon in the city and 16 on the highway. The H3 is one of largest SUVs on the market, but you can improve your fuel economy by changing your driving style, maintaining the engine and making minor adjustments to the vehicle.
Use the smallest tires possible. The engine has to work harder to rotate large tires.
Remove excess weight from the trunk. The H3 weighs 3 tons, and excess weight only makes the engine work harder. Remove the roof rack from your H3 if you are not using it.
Change the oil every 3,000 miles with the correct grade of oil. While you are getting an oil change, make sure the mechanic checks the air filter, tops off all fluids and checks the tire pressure. A dirty air filter and low tire pressure reduce fuel economy. Check your tire pressure every month.
Change your driving style. Do not floor the gas pedal to accelerate quickly or drive at high speeds. Set the cruise control at the speed limit on the freeway. Rather than breaking hard for an upcoming stop, anticipate the stop and let up on the gas pedal in advance. Altering your driving style is the best way to improve fuel economy.
Avoid driving during rush hour. Idling in traffic for more than a few minutes burns gas and reduces your fuel economy. Turn off your H3 if you are waiting in a parking lot, and don't let the car idle to warm up in the morning. If the temperature is under 30 degrees F, it takes an H3 less than a minute to warm up.
