Actually liquid gasoline does not burn.Liquid hydrocarbons must vaporize to burn. As an example, during a tank fire in a refinery, if possible you would pump out as much liquid as possible under the fire.Then you would let the rest vaporize until the fire burns out. I have fought a few as a fire captain for 20 years in a refinery/ chem plant. The thing that would cause the most trouble, is if the liquid got hot enough to boil. Then it would cause large amounts to vaporize. That is where you have the explosions.This is why, when fighting this kind of fire, you use all the water you can spray on the outside of the vessel. You are trying to keep the liquid cool as you remove it. Another example is lighting a bbq pit. You pour the starter liquid in it, the back off and throw a match. Whoom, some has vaporized and the match reached the area where the mixture with O2 is right. After the initial boom, if you make it up to the pit you will still see some liquid. Getting to Tal, yes a cig can catch gas vapors on fire, also static electricity from a cell phone or other sources, also lightning, even leaving the engine running. Just saying, the vapor burns, not the liquid. One more thing, Vapor won't burn if it is too "rich". you need the right mixture of vapor/O2 and and igniter.