yep...we say we use a "gas stove" ...but when speaking of fuel, 'gas' for your car is just understood in context to be short for gasoline. So far, 'liquified gas' is uncommon enough that one just uses the whole term..

(No particular justification for it all...just as 'torch' in used in the UK to mean either a battery powered gadget OR a flame on a stick.)

I'd be hard put to choose one term over another...'petrol' makes a certain amount of sense, but 'petroleum' here means the raw product, which is commonly abbreviated to 'oil'...and I'd suspect that 'gas' is used partly because it's shorter..