◊ 'gas'
The air-like substance that burns easily and that is used for cooking and heating is called gas.
\
In American English, the liquid that is used as fuel for motor vehicles is also called gas, or sometimes gasoline.
I'm sorry I'm late. I had to stop for gas.
◊ 'petrol'
In British English, this liquid is called petrol.
Petrol only costs 30p per gallon there.
Useful english dictionary. 2012.