(All cost savings are based on an assumed fuel price of $2.91/gallon.)
Drive sensibly: Aggressive driving (speeding, rapid acceleration and braking) wastes gas. It can lower your gas mileage by 33 percent at highway speeds and by 5 percent around town.The articles I've read stressed that driving slower is the best way to conserve gas.
Fuel Economy Benefit: 5-33%
Equivalent Gasoline Savings: $0.15-$0.96/gallon
Observe the speed limit: While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph. As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas.
Fuel Economy Benefit: 7-23%
Equivalent Gasoline Savings: $0.20-$0.67/gallon
Remove excess weight: Avoid keeping unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your MPG by up to 2%. The reduction is based on the percentage of extra weight relative to the vehicle's weight and affects smaller vehicles more than larger ones.
Fuel Economy Benefit: 1-2%/100 lbs
Equivalent Gasoline Savings: $0.03-$0.06/gallon
Most modern vehicles deliver their best fuel economy in the 50-to 60-mph range. We're talking 3 to 5 miles per gallon better mileage than the same vehicle delivers at 75-plus mph.If your vehicle has a 20 gallon tank, you could drive 60-100 miles further if you reduced your speed. That's a significant savings. Just be careful with any money you save though. If you spend it on fast food and gain weight, your savings will go right out the door.
Update: Kvatch @ Blognonymous left some other good tips to help you conserve gas in the comment section. Check them out and feel free to leave a few of your own.