[mattlondon]

Well equally why does the US call the liquid you put in your car gas? :)

No one calls it petroleum - petrol is what anyone on the street would call it. Diesel is different and just called diesel. I don't know why or how this started - guessing some old thing that wasn't-quite-right but which stuck around regardless

[mecsred]

Fair point, it is also confusing, but gas and gas are two different words. One is a phase of matter and the other is a shortened form of gasoline, much like petrol/petroleum. However, gasoline does actually go in the fuel tank of your car.