(1) Mow your lawn much less frequently. Kick back, have a beer, enjoy your Saturday afternoon. Its the patriotic thing to do.
(2) Do you really need to go to service/mass/temple as often as your do? Stay home and pray from your living room. God is everywhere and he doesn't want you wasting gas.
(3) Nothing kills efficiency and wastes gas as much as braking. Avoid the natural tendency to brake when you see a stale yellow light, a dog or squirrel on the side of the road, or road construction.
(4) Draft the eighteen wheelers on the freeway. On the expressways get within a foot behind them and it really cuts down on wind resistance.
(5) Don't allow any passengers in your car that weigh more than 185 pounds. Nuff said.