Americans are gas gluttons compared to what?   Third world countries?   Yes and we are food gluttons, energy gluttons, money gluttons, healthcare gluttons, length of life gluttons etc compared to those countries too.   But if you want to live in a shack without heat, water or electricity, I can tell you some great places you can accomplish that.   If you don't want to know the next time you will eat in a WEEK, (not merely miss one meal) so you know what it's like to be hungry I can tell you some places you can go for that experience too.   

On the other hand we could make much more efficient vehicles at the cost of capacity and safety.   You won't find a truck capable of delivering 20 tons of food that gets 100 mpg.  But I could make a motorbike that would get 100 mpg pretty easily if I cut all the weight and safety features off of it.   I just don't know how many fools would ride it.