5. Got shade?Also I heard you should only keep it half full at all times for the same reason...the lighter the better.
Buy a good windshield shade. A windshield shade blocks sunlight and helps to keep heat out of the inside of your car. This will help reduce air conditioning use in the summer.
8. Tighten that cap.
Gas will evaporate from your car's gas tank if it has an escape. Loose, missing, or damaged gas caps cause millions of gallons of gas to evaporate each year.
9. Wait until you're near empty.
Don't fill up until your tank is near empty; this will extend your gas because you are hauling a lighter load as the tank nears empty.
33. Lose the racks.
Remove ski, bicycle, or luggage racks from your roof if you don't need it. They also cause air drag.
35. Trucks, drop the tailgate.
You will get more mileage if you put down the tailgate due to less wind resistance.
61. Forward only.
Park your car so that you can later begin to travel in forward gear; avoiding reverse gear maneuvers will save gas
While on the subject of cars and energy, I found this great article on "Greening Parking Lots With Solar Trees". It's a very intriguing idea, using the waste of space as an opportunity to harvest energy. In the future, these "solar trees" will supposedly be lining the streets as well. It's just amazing to think of what the future will hold.