The Ray Sphere was a device used by transferring the neuro-electric energy from a group of people to concentrate it into a human indevidual to unlock his/her powers. Though it will unlock the dormant abilities of the Conduit, it will kill the catalysts, and worse, cause a catastrophic explosion.
How many gallons of gas does the average mid-size car hold? The average fuel tank size for mid-size cars is 16 gallons. If the  price of gas was $3.59 per gallon, it would cost $57.44 to fill a  16 gallon tank.
The gas tank holds 11.9 gallons, but it's not unusual to only get 8-9 in when the last pip starts blinking. At 2 pips left, 7-8 gallons seems about right.