X number of miles per one gallon of fuel???

I had a thought a few years back about what it actually means to go X number of miles per one gallon of fuel. Sure we all want to go a great distance on one (US) gallon of fuel due to a number of factors.
Lets see, environment, cost, that smaller "carbon footprint" stuff we keep reading about. While some of us are on the fence, over the fence, or standing at the fence with a gun, when it comes to what impact the environment is taking via fossil fuel consumption, this argument (blog) is simply a distance traveled argument. Nothing more. No opinions on if we are killing ourselves via automobile travel will be spewed into your eyeballs here (its a hoax)... promise.
Now, the topic at hand. I like to travel this far >............< on one gallon of fuel is quite an idea in and of itself. Somebody somewhere had to say it first: "Well gooollleee, we went us 12 of them miles on that one there gallon of gas MeeMaw." That's my version of the conversation anyway. But now days we get all bent out of shape when our vehicle fails to travel 25,30,35 miles per one gallon of fuel (MPG). The idea is ingrained in us, due to environmental sillies, and the numbers glaring at us on the window sticker of our future new car, (put there by the government...shhh) that we should be able to travel some sort of distance using only one gallon of fuel. Results may vary. But you have a good ballpark figure there on the window to go by at least.
It has been my experience all but one time, meaning only with one vehicle out of many, that I can easily achieve a better number than what the government group says - and usually the numbers are well within the "results may vary" numbers. How they come up with the BIG number glaring at you from the page I dunno.. side note.. Ever wonder why that number is bigger and more "important" than the, actual price number?? Odd.
So a few years a go I was thinking - if I get a gallon jug, fill it full of water, take the lid off and take off walking while trying to be as efficient as possible pouring out the water onto the road I bet I would make it what a quarter, maybe half a mile? Seriously. I don't think I would make it anywhere close to 25 miles!! And that's just me by myself with my own little pouring routine trying to be as efficient as possible walking. WALKING down the road. And we gripe that a fully loaded, climate controlled, soft seated, safety cage traveling at lord knows what speed with 4 of our friends only gets us 25 miles with the same measured gallon of fuel?? Environmental nerds aside that's friggn COOL!!