Although a spark is where gasoline gets ignited the easiest even a good enough flame can start gasoline on fire such as through use of a torch.
Sometimes even a match can set gasoline on fire but usually to get the fire going fast a good handheld torch is needed to ignite the gasoline and get it going.
Also if you were to throw gasoline onto a fire then it will ignite right away and flash back at you and burn you so you should never do that.
Gasoline works to make an engine run by getting ignited in the cylinders of the engine by the spark plugs in the engine and the electrical current that your engine produces.
Your ignition coils also produce the voltage to allow the gasoline to ignite properly and allow the engine to create an explosion in the cylinders which is what makes your engine run and propels your vehicle.