There is a group fanatics called "hypermilers." These nut cases try to squeeze every possible mile out of the fuel they put into their cars. See them in action at http://www.hypermiling.com/ To hear these whackos, you'd think that money doesn't grow on trees, that we shouldn't waste fuel - even though we can.

Ignore those looneys! Here are some tips to help you save on driving costs (and steralthily emulate their bizarre ways).

We'll skip the obvious:
• go easy on the gas pedal
• avoid necessary driving
• use cruise control
• keep tires properly inflated (save up to 5 cents/mile for fuel plus longer tire life)
• drive a gas-sipping car

Let's look at the not-so-obvious:
• Turn off the engine instead of letting it idle unnecessarily. "For modern, fuel-injected vehicles, the break-even point for turning off the engine and then restarting it right before traffic begins to flow may be as little as 10 seconds, even when considering extra wear on the starter motor, battery and other components."¹ At the drive-up window, turn off the engine while exchanging money for that artery-clooging snack. You'll save money - and the guy inside the window - the one in the funny hat - will appreciate not having inhale your car's exhaust.
• Say 'thanks, but no thanks' to the E85 ethanol. Alcohol contains less energy per unit (per gallon) than gasoline. That means that it takes more ethanol or ethanol-mix (like E85) to go the same distance. The EPA says you'll get about 7 mpg less with E85 (85 percent ethanol, 15 percent gasoline) than with 100 percent gas.
• If your car needs premium fuel, buy premium fuel. Going on the cheap here will cost you. Lower octane fuel forces the engine to work harder to achieve the same performance. According to Lexus, using 87-octane fuel in its vehicles that require 91 octane will reduce fuel mileage by about 6 mpg. Note: the opposite is not necessarily true. Using premium when regular is OK will not improve performance significantly.
• Plan your trips. Engines use the least fuel when operating most efficiently. Maximum efficiency requires that the engine be warmed up. Think about ways to get - and keep - the engine warmed up. For example, on an errand trip with many stops, drive first to your furthest destination and make your other stops on the way home.
• Think: maintenance. This is a big one!
  • A clogged air filter wastes fuel. Change it as needed (check your auto's owner's manual).
  • That "check engine" light.... it usually means that the oxygen sensor needs replacing. Of course, you could ignore the light, or (I love this one) cover it with a piece of black tape so that darned light doesn't annoy you.
  • On well-built cars, your suspension will never need alignment - unless you ram curbs (and other cars). But an out-of-spec will burn more fuel ... and eat up your tires
  • Use the proper engine lubricating oil. Too-heavy an oil stresses the engine into using more fuel. What's the proper fuel? RTFM. It's in your car's owner's manual.
• Forego the bric-a-brac. Non-stock exterior add-ons will simultaneously increase wind resistance and fuel consumption. Wings, roof racks, running boards, fender flares, brush guards, and the like add to your fuel costs. You could take off the ski rack in the summer²....

¹ edmunds.com
² Surfers (wave surfers) can ignore this. One never knows when King Neptune will send a present, in the form of good waves. Year-round board racks are a necessity - for those Surf's Up! emergencies. It's a trade-off - waste gas, preserve sanity. Surfers (wave riders, not keyboard jockies) know what I mean: sometimes you have to leave some carbon footprints in the line-up.