word usage – Are both gasoline and mains gas called “gas” in the USA? – English Language & Usage Stack Exchange

Yes, American English uses gas for both meanings. In fact, you’ve hinted at another: In your example gas is being used not only for petrol but as a shorthand for “natural gas.” We would also use gas for the broad physics meaning of a state of matter: “Oxygen is a gas at room temperature and atmospheric pressure.” We would speak of nitrogen gas, neon gas, etc.

Confusingly, we also regularly refer to liquid propane as “gas”: “The grill is out of gas. I’ll have to go exchange the gas canister for a full one.” —Which is, of course, a liquid, at least in the canister. I presume the British don’t engage in this madness, but maybe someone can chime in to enlighten me whether they call it petrol as well.

DjinTonic’s point stands: context is powerful. We have plenty of words that serve multiple meanings (consider poor multi-tasking on!), and context usually eliminates confusion. If you walk up to a blindfolded American stranger and blurt out “I got gas!” then yes, they won’t know whether you mean that you topped up the car, got a canister of LP, or perhaps are suffering from indigestion. But if they can open their eyes and see the grill tank you’re holding, the petrol pump and car beside you, or your roll of Tums (or better yet, if you have the common decency to establish some conversational context before diving in!)*, they’re in the clear.

* I know someone who is terrible about this. The other day he launched a conversation by talking about his difficulty with his router, and was a few sentences in before I realized he was talking about woodworking rather than home wi-fi.