Gasoline is liquid but gasses on the periodic table of elements are fumes, so why do we call the stuff we put into our vehicles "gas," if it's liquid?

Because "gas" is an informal and quicker way of saying gasoline that was adopted by the general public for convenience sake.

Language doesn't exist to be technically correct, it exists to facilitate practical conversation. The more you look at it from this perspective the more things will start to make sense.

It's called petrol and benzin elsewhere in the world. Gas/gasoline is just a name for automobile fuel.

Btw, on the periodic table at room temperature and typical atmospheric conditions, gases are "fumes", sure, but all of the first 72 elements are gaseous at 5000°C.

“Is H2O a gas or a liquid?” - Dr Octogon

I know that there are "no stupid questions," but this is an EXTREMELY not stupid question. On the contrary, it's fascinating and non-intuitive.