I am a technician, I trust none, I have to test for myself.
Partially filled a gas can, exactly 0.4 gallons. Carried that gas can when the bike's gauge was saying empty. Finally the gas light started flickering. 5-10 miles later gas light solid. About 40-50 miles later the started sputtering. Bike does a "Run? Maybe? Yes? No?" and went a 1/4-1/2 mile before actually stopped. Nice to know that when I run out of gasoline it is not a just stop. Put the 0.4 gallons in the tank, gas light stays on solid. I now know that I have at least 0.4 gallons when the gas light tells it is really really low. The gas station was about 2 blocks ahead.
Managed 144.2 miles from last fillup, counting the .4 gallons I had been carrying the tank took 2.127 gallons, a little under the nominal 2.3 gallons. 68 mpg, 100% city, I am not allowed to go on the freeway yet.