A prankster wrote in to Click and Clack to say that he and his buddies had added gas to a co-worker’s FIAT to hear him brag about the fantastic mileage he was getting. Then they started siphoning gas out and his MPG plumeted.
That was a partial plot line in a 1972 movie “Pete and Tillie” starring Carol Burnett and the deceased Walter Matthau. Only the car was an orange VW IIRC. http://www.imdb.com/title/tt0069080/
That was a funny story about the Fiat owner. Here’s my own siphoning story.
In my first year at college, one of my dorm chums had a Ford and his roommate had a VW Karmann Ghia. The Ford guy, he started to notice his gasoline bill was higher than normal. Thinking something strange is afoot, he monitored the Ford’s gas gauge, and discovered it was going down abruptly every Thursday night. He was loosing 1/4 of a tank every Thursday overnight from his Ford. It turned out, he discovered his roommate was secretely siphoning gas from the Ford, in order that the roommate would have enough gas in his Karmann Ghia Friday for his Friday night dates.
So what happened? The Ford guy removed the fuel inlet hose from the filler on his car, and extended that hose into the trunk instead, so he could still refuel his Ford. To the Ford’s filler – you can probably guess – he attached another hose which went to a 2 gallon jug, half gasoline, half water.
The siphoning stopped straight-away!