If you're really unhappy with the tank not being full, you could immediately fill the tank at a station close to the rental car office as soon as you pick up the car. If you can put in 2.5 gallons, then you can complain.

I have experienced a less than full tank but that is not that common. Fortunately, not everyone is a cheapskate and fraudster.

Renting a car from midtown Manhattan is a different story. There are no gas stations in Manhattan below Harlem. At least none that I know of. The Mobil station on the west side closed long time ago.