/counter nitpick on
It is correct to call a gasoline powered engine a motor. Engines are a subset of motors, just like electric and rocket motors are both subsets of motors.
Analogy:
The term vehicle instead of motor. You can call a car, a truck, or a plane a vehicle. Just because you might not commonly call a plane a vehicle, doesn't mean it isn't one.

A glow or gas engine fits the definition of motor, so they are correctly called motors. Less accurate, yes. Not incorrect. Practically interchangable terms here in north america.



On to "gas"....

Gas is short for gasoline, which in the uk, i believe is commonly called 'petrol', short for petroleum.

pe·tro·le·um n.

A thick, flammable, yellow-to-black mixture of gaseous, liquid, and solid hydrocarbons that occurs naturally beneath the earth's surface, can be separated into fractions including natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, and asphalt and is used as raw material for a wide variety of derivative products.


gas·o·line n.

A volatile mixture of flammable liquid hydrocarbons derived chiefly from crude petroleum and used principally as a fuel for internal-combustion engines.


Looks like the term 'gas' is probably the more correct term. Although when both parties know what is being referred to, correctness is irrelevant.

And to use your trick of using the word gas to describe the state of matter.... internal combustion engines burn their fuel in a gaseous form. In the fuel tank and lines, fuel is in liquid form. The carb converts the fuel to a gaseous form while mixing it with air. Regardless of the fuel used, the motor is burning 'gas'


fun fun,
I hope i don't regret this.