[kevenj]

Best thing you can do to maximize efficiency is to keep up on maintenance; change plugs as recommended at 30k miles, change your air filter before it gets completely packed with dirt - - many people wait way to long on this because it's kind of 'out of sight, out of mind' but it can make a difference. I would stick with a good quality paper filter rather than a K&N style because you will trap more dirt in a decent paper filter (Wix, NapaGold, etc...not FRAM!). Another thing is keep the tire pressures correct, maybe even a couple psi over the recommended 30 psi - - but I wouldn't go over 32 or you'll end up with tires wearing in the center and a harsher ride.

There's really nothing "magic" you can do, just this common sense stuff. There's a lot of "snake oil" for sale now that gas prices have gotten so high, but all most of those products do is make it easier for the seller of them to afford the high gas prices!