Ya really gotta cut the weight, then you can disconnect 2 sparkplugs and shove a dead squirrel or something in the intake to reduce the flow (less air, less gas). These modifications should get you up to the 60 to 70 mpg range.
Most cars come with lots 'o parts. Waaaay more than you really need. Just look at this picture. If you don't recognize it, you probably don't need it. They just put all that stuff in there so they can charge you more money. Just start takin stuff off. If it stops runnin, put it back and take something else off. You can probably get the weight down to that of a garden tractor. Come to think of it, yank out that gas guzzler under the hood and swap in a Briggs & Stratton!!
Waaaaaay too many parts..............