03 mustang gt

Let me guess. 0 to 60 in 6 seconds at every stop light? Been messing with the engine? Eliminated the cat and O2 sensors?

Never use a fuel gauge to estimate mileage, they're not that accurate. Fill the tank then drive a distance refill the tank to the same level like when the pump shuts off then do the mileage estimate.

That’s funny. 0-60 in 6 seconds at every stop sign or light.

No. The vehicle is driven normal about 2k for shifting . Engine is stock. Cats and i belive 02s were removed by previous owner

No

Cats and O2 sensors removed means the fuel air ratio is all screwed up. Put it back together and your fuel economy should return.