posted from: http://www.ftc.gov/bcp/conline/pubs/autos/gasave.htm
Shifting Gears: Real Money-Saving Steps
There are numerous no- or low-cost steps you can take to combat rising gas prices. The most important place to start is at the gas pump; buy only the octane level gas you need. All gas pumps must post the octane rating of the gas under the FTC's Fuel Rating Rule. Remember, the higher the octane, the higher the price. Check your owner's manual to determine the right octane level for your car.
Here are some additional tips from the EPA to help you get better gas mileage.
Drive more efficiently
Stay within posted speed limits. The faster you drive, the more fuel you use. For example, driving at 65 miles per hour (mph), rather than 55 mph, increases fuel consumption by 20 percent. Driving at 75 mph, rather than 65 mph, increases fuel consumption by another 25 percent.
Use overdrive gears. Overdrive gears improve the fuel economy of your car during highway driving. Your car's engine speed decreases when you use overdrive. This reduces both fuel consumption and engine wear.
Use cruise control. Using cruise control on highway trips can help you maintain a constant speed and, in most cases, reduce your fuel consumption.
Anticipate driving situations. If you anticipate traffic conditions and don't tailgate, you can avoid unnecessary braking and acceleration, and improve your fuel economy by 5 to 10 percent. In city driving, nearly 50 percent of the energy needed to power your car goes to acceleration. Go easy on the gas pedal and brakes. "Jack-rabbit" starts and sudden stops are wasteful.
Avoid unnecessary idling. Turn off the engine if you anticipate a lengthy wait. No matter how efficient your car is, unnecessary idling wastes fuel, costs you money and pollutes the air.
Combine errands. Several short trips taken from a cold start can use twice as much fuel as one trip covering the same distance when the engine is warm.
Remove excess weight from the trunk. Avoid carrying unneeded items, especially heavy ones. An extra 100 pounds in the trunk reduces a typical car's fuel economy by one to two percent.
Maintain your car
Keep your engine tuned. Studies have shown that a poorly tuned engine can increase fuel consumption by as much as 10 to 20 percent depending on a car's condition. Follow the recommended maintenance schedule in your owner's manual; you'll save fuel and your car will run better and last longer.
Keep your tires properly inflated and aligned. Car manufacturers must place a label in the car stating the correct tire pressure. The label usually is on the edge of the door or door jamb, in the glove box, or on the inside of the gas cap cover. If the label lists a psi (pounds per square inch) range, use the higher number to maximize your fuel efficiency. Underinflated tires cause fuel consumption to increase by six percent.
Change your oil. Clean oil reduces wear caused by friction between moving parts and removes harmful substances from the engine. Change your oil as recommended by the vehicle manufacturer.
Check and replace air filters regularly. Your car's air filter keeps impurities in the air from damaging internal engine components. Not only will replacing a dirty air filter improve your fuel economy, it also will protect your engine. Clogged filters can cause up to a 10 percent increase in fuel consumption.
Consider buying a fuel efficient vehicle
Deciding which vehicle to buy may be the most important fuel economy decision you make. The difference between a car that gets 20 MPG (miles per gallon) and one that gets 30 MPG amounts to $3,125 over 5 years, assuming gas costs $2.50 per gallon and you drive 15,000 miles a year.
for more information. Youâ€™ll find gas mileage estimates and other data from EPA for 1985-2007 model year cars.