[slomotion]

Not exactly a testament to mileage, but we thought it was amusing....
Back in the 60's I was stationed on a ship who had an electrician that was into all the gimmicks to increase mileage. He ordered some little fan gizmo that attached to the top of his single barrel carb. This "Turbo Jet something, something" had a wire sticking out of it and he wired it to a toggle switch so he could "monitor the data".
One duty night we added a quart of gas to his tank. Three days later we did it again. This went on for a couple weeks and he started bragging about his mileage being increased even better than he thought it would. We stopped adding gas for a couple of weeks and he began to get puzzled that the mileage was "dropping off". Then we started siphoning out a quart on regular intervals. This drove him crazy.
We never learned who outed us, but somebody did and we had to find another source of amusement.