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.
In the US, a standard oval-shaped tank is rated to hold 275 gallons when completely full. Typical actual capacity is around 250 gallons or so. If your gauge is accurate, you should have something around 200 gallons of oil if 3/4 full.